Load the camera. Advance the film to the first frame. Set the shutter to B. Trip the shutter with a cable release and lock it open (film is exposed obviously). Look through the lens mount. Hold the camera so a centerpost of a window, a pencil or similar dark straight object with a light background is reflected onto the film.

A perfectly flat film should reflect a straight post or pencil image. If you see any distortion, bulges, twists, or squigglies - you have a real problem.

In Mr. Maersk-Moller's experience, nearly all the 2 1/4 inch SLRs and 60% of the 35mm SLRS have noticeable film buckling.

By putting a thin glass plate at the film plane, flatness can be assured, and lens performance improved (especially at wide open apertures). He provides some figures for a Praktisix Zeiss Biometar f/2.8 which was improved from unacceptable to excellent over most of its range. A thin glass (microscope slide thick 0.01 to 0.03 inches thin glass) can be used in place of his thicker installed plates for testing.

From: How to Flatten Your Film for Sharper Pictures by Hans Maersk-Moller, Modern Photography, April 1970, pp.78-79, 120.

The key points here are that lots of cameras, particularly 6x6cm and most 35mm cameras, have visible film buckling. You can use his test to see if your camera does too. Whether you want to try his solution, at least you know now that the lens is not always to blame for wide open errors and softness - it may be your buckled film.

    As Larry (Hemi4268) note:

Film flatness only comes into play with large f numbers.  To get an idea of allowable film flatness in microns simply take the f-stop and square it.

TABLE THREE
f1= 1microns = 0.001 mm
f2= 4            = 0.004 mm
f4= 16          = 0.016 mm
f8= 64          = 0.064 mm
f16=256       = 0.256 mm
f32=1024     = 1.024 mm
f64=4096 or 4 mm

    Table three  is quite interesting if you accept the usual values of 0.2mm for a combined error for both depth of focus and film flatness. Basically, you run the risk of problems with film flatness and focusing errors at or below f/16, per table three. But from table two, diffraction will limit us to about 70 lpmm at f/22, for a maximum magnification (to 8 lpmm) of 8.9X on 4x5 format. Again, this figure doesn't factor in losses from aerial lens resolution/diffraction to on-film resolution, which typically run about 50% or so. If we factor in these losses, the results are in excellent agreement with Harris' study quoted below (viz. 9.2x at f/22 using TP but at 4 lpmm).

Case Study - LF vs MF:

    Thanks again to Michael Gudzinowicz, we have Harris' figures comparing LF and MF, viz:
 

One of the best studies of on-film resolution was done by Dr. Ron
Harris (D&CCT, Mar/Apr 1991, p.26) in which he compared formats using
Tech Pan.  Also, different films were compared using a Hassy and 80mm T*
Planar at various apertures, checking high, medium and low contrast
targets on- and off-axis.  Focus was checked and locked, and appears
precise.

Using a Symmar S 210 @ f/22, TP gave on axis resolutions of 44, 42, and
34 lpmm for the different contrast targets, and 37 lpmm for the corner
(high contrast).  The optimal on-axis f/stop for the Hassy was f/8,
giving 72, 72, and 45 lpmm on axis for different contrasts, and 34
lpmm  in the corner.  Note that if we ended the comparison at this point,
corner sharpness is the same for both formats.

Optimal corner resolution for the 80 T* using TP, TMX, APX 100, TMY and
Tri-X occured at f/16.  For TP, the corner value was 45 lpmm at f/16.

Harris gives the following print sizes as the maximum which just
acceptable for corner to corner sharpness using TP.  The "eye" refers to
evaluation by eye (4 lpmm in the print) and the loupe figure refers to
sharpness evaluated with a loupe, limited to 13 lpmm by the paper.

35mm  Pentax 50mm f/2.8 macro @ f/8       16 x 20      4.5 x 6
Hassy 80 mm f/2.8  T* Planar  @ f/16          27 x 27      8 x 8
Wista with 210 f/5.6 Symmar S @ f/22         37 x 46     11 x 14

Enlargement Gap:

    We observe that 35mm is enlarged about 14x, square medium format (2 1/4 square) is enlarged about 12x, while LF 4x5 is enlarged only 9.2 times.  Obviously, these enlargement differences are directly related to the film resolution differences highlighted above. Had we used the Leica standard of 8 lpmm for critical sharpness, these values would be halved, but otherwise similar.

    The enlargement gap is simply the difference between 14x on 35mm and 12x on MF, and 12x on MF vs. 9x on LF. Since 4 inches is 1.78 times 2 1/4 inches of square format image size, the corresponding magnification is only 37/27 or 1.37 times. On this limiting axis, we are only getting 37/78 or circa 45% of the benefits we would expect from geometry alone (1.78x). While we increased the limiting film axis dimension by 78%, we could only increase the resulting enlargement axis by 37%.
 

We got only 45% of the expected benefits from film geometry by going from MF to LF.

 

Caveats:

    Some caveats are still necessary.  Large format enjoys several major advantages over both 35mm and medium format, including tonal gradation, grain size, and acutance (as pointed out by Michael Gudzinowicz). Grain size may become particularly important beyond enlargements of 8X in this view. While tilt/shift movements are not exclusively found in large format, they are also a common benefit to LF photography.

    Conversely, the 35mm and medium format photographer thinks very little of focusing and shooting at f/2.8. This capability is impossible with most LF lenses. Even relatively fast LF lenses are rarely used wide open except for focusing, and usually closed down significantly in practical use. This technique masks the problems that would be encountered with film flatness and focusing errors if these LF lenses were used at more wide open f/stops.

    Marc Hult correctly observes that prices for LF lenses are not more expensive than prices for new MF (especially Hasselblad) and Nikon (35mm) lenses. However, it is evidently true that many 35mm third party lenses of modest cost have equal or higher on-film resolution than either the pricey Hasselblad or LF lenses cited above. Again, the larger MF and LF glass size and lens aberration and correction issues would make it surprising if this wasn't true.

    Kerry Thalmann suggests that film costs are also lowest for medium format:

The cost of the film, per square inch of image area is actually highest for 35mm (about $0.11 per sq. in. for Velvia) and lowest for 120 medium format (about $0.055 per sq. in.), with 4x5 sheet film falling in between (about $0.085 per sq. in.).

    The analysis above suggests that LF photographers are caught between film flatness and focusing effects (table three) and diffraction (table two). The higher the degree of magnification, the narrower is the allowable range between diffraction and focusing/flatness errors, as shown by tables one and three. Diffraction limits the range of higher f/stops available at high magnification, while film flatness and focusing errors make it hard to use the smaller f/stops effectively.

    Moreover, lens coverage issues and lens aberrations and correction practices favor smaller apertures on LF. Nonetheless, it is disconcerting to have a relatively fast LF lens (say, f4.5) that should and would be used at f/22 in most LF situations.

Conclusions:

    1) From Harris' data, we infer that 35mm >> MF > LF resolution in lpmm on TP film (current film, lenses..). LF lenses still have lower resolution than 35mm and MF lenses or 16mm. This is exactly what we would expect from aerial image resolution data, and lens aberrations effects...

    2) Harris' data also suggests that 35mm can be enlarged 14X, MF by 12X, but LF only 9X.
Again, this is another way of restating that lens and film resolution are different (see (1) above).

    3) From geometry, we would expect to be able to enlarge 4x5 film 1.78X or 78% more than MF (6x6cm). Our observed enlargement is only 1.37X, or 37% per Harris. So we are only getting 37%/78% or 45% of the expected benefits from the larger format film over MF.

    4) The costs of that 37% greater LF enlargement are high, not only in film costs and bulkiness, but also in terms of limitations on allowable apertures, especially at the higher enlargement ranges.

    5) Film flatness and depth of focus errors are still an issue, especially at wider apertures. Conversely, diffraction plays a limiting role especially at narrower apertures and high enlargement.

    6) This analysis ignores some benefits from larger LF film size, including acutance and tonal gradation, as well as ability to use tilts and shifts to place plane of focus where desired on image.

We also ignore the many abilities of 35mm and MF to use wider apertures and greater portability. We used the limiting (smaller) axis for enlargement comparisons, rather than area, but other MF cameras could be picked for 35mm (6x9) or 4x5 (6x7) equivalence.

    7) Being over double the size of 35mm (56mm vs. 24mm), the slightly higher enlargement factor of 35mm (14x vs. 12x for MF, or 16% more enlarge-ability than MF) is swamped by the more than double (2.33x) film size of MF. Conversely, the over 3/4ths larger film size of 4x5 film only provides a 37% potential increase in enlargement, or less than half (45%) of the expected benefit.
 

MF gives arguably the best bang for the buck (film costs) and enlargement capability

Lens Resolution - What you get

Newsgroups: rec.photo.equipment.large-format
From: [email protected]
Subject: Film holders  

I recently read some where a discussion on the relative merits of different
film holders.  I think the conclusion was that the Grafmatic type held the
film the flatest and the Fuji Quickload was also good.

I would like to hear any of your comments on these and other film-backs like
the Kodak Readyload and standard holders.

Thanks.

Bob 

rec.photo.equipment.large-format
From: [email protected]
[1] Hi-(medium- ???) tech 4x5 film holders
Date: Fri Apr 03 14:06:12 CST 1998
I need maximum (affordable) film flatness delivered from 4x5 sheet film. When I called Calumet Photo, the sales rep said all they carry is Fidelity and Lisco film holders --- probably the same type I worked with 35 years ago. (BTW, which brand is currently better?)

Seems like I heard someone (Arca-Swiss?, Linhof?) was making a 4x5 holder that actually is sticky to the mulsion and keps the film from buckling??? What's the scoop on this? Anybody try double sided tape?

I am not ready to climb ladders with a vacuum pump, so please don't suggest a vacuum-type holder (shades of graphic arts).

Any useful info most appreciatd.

[email protected]

Wayne Catalano 504-271-1507 (voice and fax)

rec.photo.equipment.large-format
From: [email protected] (Richard Knoppow)
[1] Re: image circle question
Date: Sun Apr 05 01:35:48 CST 1998

"Josef" [email protected] wrote:

>Is it true that lenses with smaller image circle produce sharper images
>than those with larger image circles (assume same glass, same f )?  If this
>is ture, is that mean 35mm lenses are sharper than LF lenses??
>
>
>Does anybody know a good book that explains what determines Image circle in
>lens design?  I am puzzled why lenses with same focal length, f, can have
>different image circle sizes.
>   

I've been trying to figure out how to answer this without getting too technical and complicated.

Lens coverage is limited by design. For a lens to cover a wider angle the light must be able to enter the lens and travel through it at greater angles. That makes it harder to correct the lens. The aberrations or lens faults are largly proportional to the angles which the light rays make with the glass surfaces in the lens. That is why lenses get better as they are stopped down. The smaller opening limites the range of angles which light from any given point can take going through the lens.

Light going straight thrugh the lens isn't bent at all so is "perfect". The further away from the center of the image one gets, the more the light must be bent by the lens elements and the larger the angles invlvolved are. When the angles get too big one or more of the elements must be split into two or more elements so that the bending of the rays can be more gradual.

Ultimately, the light is blocked off from entering or leaving the lens by the body of the lens. This is known as vignetting. It is done delibrately in modern designs so that the illumated circle of light projected by the lens is no larger than the circle which is corrected to give a good quality image. This isn't true for older lenses. For instance, I have a Wollensak/Graflex Optar 15" Telephoto lens. This lens is intended to work with 4x5 cameras. However, the circle of illumination will cover an 8x10. If I examine the quality of the image away from the intended coverage area it is obvious that it is becoming rapidly blurred away from the center.

Newer designs are generally not like this.

Some types of lenses have inherantly larger coverage than others. For example, a "double Gauss" type lens, the type used for the Kodak Wide Field Ektar, is much easier to make into a wide angle lens than the "dialyte" type as used for the Apo-Artar. Even though both types use four air spaced elements. The elements in the Gauss are bent into meniscus shapes and those in the dialyte (means two windows) isn't.

Some other types of lenses simply do not have enough surfaces and spacings to correct the secondary aberration which become important with wider coverage angles. Thus it is harder to make a good WA triplet than it to make one with a Tessar, because the Tessar has another surface and bending in it.

If my understanding is correct, some aberrations scale with the focal length. So if the dimentions for a lens are simply scaled up or down the shorter lens will have better resolution than the longer one although the aberrations will still be the same when measured in proportion to FL.

So, one finds f/2.5 triplets made for 8mm motion picture cameras but not for 4x5 cameras.

The resolutin limit due to diffraction from the f/stop will be the same, however. f/8 has exactly the same limit for a 12mm lens as it does for a 300mm one.

---
Richard Knoppow
Los Angeles, Ca.
[email protected]

Date: Thu, 09 Apr 1998
From: David Seifert [email protected]
To: [email protected]
Subject: Re: [Rollei] pressure plate--wrong setting

At 11:41 AM 4/9/98 -0400, you wrote:
>Here's one for the TLR folks out there:  if the adjustable pressure plate
>on the back of my 120-only Automat had been set in the wrong position (35mm
>instead of 6x6), what problems would you expect to see in the negatives?
>
>As you might guess, this is not a hypthetical question.  I ran a few rolls
>of 120 film through the camera this way before I noticed the glitch (after
>reading Ian Parker's user's guide, by the way).  Talk about feeling stupid!
>Amazingly enough, the negatives are generally good, but there is
>inconsistent softness.  It appears in _some_ areas of _some_ negatives.
>Others look great edge to edge.  I can't see a pattern to the softness.  Is
>this what you'd expect from an improperly adjusted pressure plate?  I'm
>trying to figure out whether the softness is due to bad technique on some 
>shots (camera movement, inaccurate focus, inadequate depth of field, etc.)
>or the pressure plate.  Thanks for any thoughts you might have.
>
>--Ben McRee
>

Your results are consistent with the pressure plate being in the 35mm position without the Rolleikin apparatus in place.

The Rolleikin film gate protrudes a bit beyond the usual range of the pressure plate movement and thus requires the special 35mm position. Those who have acutally installed their Rolleikin (myself included) have tried to close the back without changing the pressure plate. The back will not close!

This is counterintuitive since one would initially think that since 35mm film is thinner than 120 with backing paper the pressure plate should be closer to the rails in the 35mm position. This is not the case. You are probably seeing the results of inadequate pressure being applied to the film and it is kind of wandering around in the channel.

Best Regards,

David Seifert
[email protected]

rec.photo.equipment.large-format
From: Gary Helfrich [email protected]
[1] Film plane distance?
Date: Sat Apr 25 15:57:16 CDT 1998

Is there a standard distance that the film plane sits relative to the front of the film holder in a 4x5 camera? I've measured a couple of Readyload holders, an Grafmatic Holder, and a Calumet 6x7 rollfilm adaptor. The first two measure 5.0mm from the front face of the holder to the film surface. The Calumet is .5mm deeper to the front surface of the film.

I've also measured the distance between the inside of the ground glass and the mounting surface on my Wista and Toyo. The Wista is 5.1mm, but the Toyo is 6.0mm.

It appears that 5mm is the nominal dimension here, but I'd like to know what this dimension should really be.

Gary Helfrich

rec.photo.equipment.large-format
From: [email protected] (Richard Knoppow)
[1] Re: Film plane distance?
Date: Sat Apr 25 22:07:50 CDT 1998

The standard is 3/16" from the reference surface of the holder to the surface of the _film_. So this must be measured with a sheet of film in place. Most cut film is 0.007 inch thick.

The reference surface is the outer surface that contacts the inside of the holder slot on the camera back. On cameras where the back is removable it is easy to measure the distance from any stable reference surface to the ground glass and check that it is the same to film in an inserted holder.

---
Richard Knoppow
Los Angeles, Ca.
[email protected]

rec.photo.equipment.large-format
From: Bob Wheeler [email protected]
[1] Re: Film plane distance?
Date: Sun Apr 26 05:34:03 CDT 1998
Richard Knoppow wrote:

> Gary Helfrich  wrote:
>
> >Richard:
> >
> >Thanks for the information.  What puzzles me is why the Toyo back is
> >deeper than this standard. I've removed the back and very carefully
> >measured the distance on a CMM, so I am sure that the Toyo is really 1mm
> >deeper.
> >
> >Gary Helfrich
> >
>   Puzzles me too, this is covered by an ISO standard and has been a
> defacto standard for nearly a century.
> ---
> Richard Knoppow
> Los Angeles, Ca.
> [email protected]

It seems that manufacturers have altered the standard to 5mm. Even so, your TOYO is too far off. I have one and it measures 5mm, as do my TOYO film holders, as does my Polaroid back.

The effect is not serious for large f-stops. For F32 you will loose about 2 lines per millimeter with the 6mm back and a 5mm holder For F8, it becomes serious -- something like 8 lines per millimeter loss.

--
Bob Wheeler --- (Reply to: [email protected])
ECHIP, Inc.

From: "John R. Williams" [email protected]
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Film plane distance?
Date: Fri, 01 May 1998

Gary,

I too am interested in film plane distances. I found that my graflock backs were all out of whack. I took the backs off the cameras, inverted them, put a sheet film holder, with film in place, and measured the depth. Then, I took out the holder and measured to the lens side of the ground glass. It WAS different. I releived away some of the casting to get the GG down to the same measurement, and ...ZOINKS...Super focus! Are you up to your old tricks again...? Can I expect a really cool Titanium 4x5 soon? Work your magic, man!

All the best,
John

rec.photo.film+labs #16246
From: [email protected]
[1] Re: How do I cut roll film?
Date: Sat May 02 05:25:59 CDT 1998

"Richard Davis" [email protected] wrote:

>(Duplicate from Darkroom news group.)
>--
>I lucked onto a roll of 5" wide film that I want to cut into 4x5 sheets for
>a field camera.  

Before you go any further you might want to test a piece and see if it is stiff enough to stay flat in a film holder. Roll film has a thinner base than sheet film, and I am sceptical that it will stay flat. I used to work in a lab printing large format roll films and they were impossible to print in any thing other than a glass carrier because they are so flimsy. A typical film holder comes into contact with a very small amount of the film; which is why sheet film is so thick. Conversely, roll film must be thin in order to conform to a small diameter spool. To make matters worse, the roll film will have a "memory" which will make the curling worse as you get closer to the end of the roll. The good news is that the film is probably wound emulsion in, which might make it lay reasonably flat because the bulge in the film will be against the back of the holder.

I wouldn't worry about scratching it when you cut it. You are more likely to scratch it when you are loading the holders, because it probably will be curled, making it difficult to load without kinks and scratches. Cover your cutting surface withe a new Ilford anti-static cloth. They are very soft and won't damage the film.

Try this: Make an "L" shaped frame of wood that is 4 inches wide and 6 inches long. Cut a block of wood to 4x5 inches and cover it all except one of the 4 inch ends with an anti-static cloth. Butt your film up into the "L" shaped frame, then put the block of wood on top. Take a razor blade or matte knife and cut along the edge of the block that does not have the static-cloth. This should work well because you can exert considerable force on the block of wood, which will keep the film from moving, and prevent scratching.

Jon Croft
[email protected]

rec.photo.equipment.large-format
From: "Christopher M. Perez" [email protected]
[1] Large Format Lens Testing madness!
Date: Wed May 06 10:53:28 CDT 1998

Kerry Thalmann and I are in the process of testing a fair number of Large Format lenses. We're starting with compact 90mm to 135mm lenses. To setup the process I attempted to test two of my own lenses. They are a 90mm Angulon f6.8 Ser#8915xxx and a 135mm Wide Field Ektar Ser#RE1xx(L).

f/stop center middle edge in lines/mm --------- 90mm Angulon f16 61/68/61 f22 61/38/38 135mm WFEktar f16 76 67 44 f22 63 63 54

The initial results compare quite well with what was reported for a Schnieder 210mm Symmar-S in the last Darkroom Technique (or ???, I can't remember the name) where that lens tested to 44 44 36 or so lines/mm at f/22. That test series was shot against Rochester's resolution charts and so will not be a direct comparison, but provides a "ballpark" feel for what's "reasonable".

Test setup was TMax100, D76 processed to my system's calibrated exposure/time/temp, Tachihara wood field 4x5, Edmonds Scientific Lens Resolution Chart. The negatives were exposed for Zone 7-8 for detailed white and Zone 3 for detailed shadow. The test setup will be changing to using a Linhof 4x5 in the hopes of providing better rigidity in the base platform, and to include readings from f/11 in the sequence, and any comments about what is read from the charts.

Kerry and I will be testing many more lenses over the next several months. The attempt will be to verify consistency across a make or lens construction (ie: Wide Field vs multi-cemented-element 105 degree lenses). As the results come available I will be constructing a URL and post a pointer to it.

I will, no doubt, re-run the tests on my lenses (something seems amiss in the Angulon's f22 reading). More importantly I'm VERY interested in seeing how old/new compact/big-coverage lenses all compare. We'll be looking at Schnieder Angulons and Symmars, Fuji A-series, Nikkor SW and M-series, Kodak Wide Field and Commercial Ektars, Congo tessars and wide fields, as well as WF Dagors, and anything else we can get our grubby leetle hands on...

Again, _my_ primary interest is in small, light, sharp, cheap lenses for use in the field.

Stay tuned... and let the madness begin...

- Chris

I forgot to add: all lenses are being tested at 1:20 (the magnification approach ing what many people, including me, actually use their lenses at - and I hope I got the ratio correct and not inverted... I'll have to recheck the std. nomenclature).

- Chris

The Lpm numbers you have just posted for the W.F. Ektar and Angulon is close t o the theoretical diffraction limit for f22. The diffraction limit is aprox. 70 Lp m for visible Green light. I think you will find similar numbers for most good vie w lenses at f22. This is why I think 50 Lpm on film is a reasonably number to expect for most lens/film combinations.

I think you will find Modern lenses will exhibit a more uniform set of numbers across the image field ( flat field ).

All this is very interesting and informative.

Benson

From: terry roth [email protected]
Subject: lens test chart
Date: 1998-05-18

I was entering a posting on the Sleicher test chart, but my carrier was dropped, so am reposting. The title should actually convey the idea that the chart measures resolution to 160 lines/mm, but it is the resolution of the entire camera system, including camera, camera support, lens, film, technique, etc.

There are 84 targets with 14 pairs of grids in 4 colors (including black) on this 2X3 foot chart. I have attained resolution of 120 l/mm with my Mamiya 7, on Kodak tech pan developed in TD-3. There is a hint of resolution at 140 l/mm, but there is some residual astigmatism and I am not sure the vertical group is resolved (at 100X in a Nikon lab microscope.) Needless to say, this is very nearly at the limits of even Tech pan--the grain, nearly imperceptible in normal size enlargements, in beginning to overwhelm the grid at this magnification. The grid lines (there are 10 horizontal and 10 vertical lines in each of the 14 groups (20 to 160 lines/mm), and the lines of the 160 l/mm grid are less than 0.00015 inches apart on the film.

I got the target at a local pro shop, it is also available for $28 from Mr. Sleicher , a 10-page instruction manual with helpful info on achieving highest resolution is included.

His address is Charles Sleicher, 5002 Harold PL NE, Seattle Wa 98105. I am not affiliated in any way, other than being a very satisfied user. He suggests using a high quality microscope to view the negatives, but I have found that the enlarger using a good quality enlarging lens, (Nikon, Componon, or Rodagon) and a good focusing magnifer with the enlarger all the way at the top of the column gives comparable results, but a little more difficult to center the various targets at the edges.

I would be interested to hear of other's experience with this chart, especially if you can achieve better resolution with Tech Pan in other developers. 120 lines/mm is fugitive---if you develop at 70 degrees rather than 65, resolution limits at 100 lines/mm. Wet time is an issue, as is agitation scheme. (I use 22 min at 65-68degrees, agitation every 3 minutes in TD-3).

I have tried TMAX-100 in XTOL, grain limits resolution to about 80-90 lines/mm. About the same for Delta 100 in PMK pyro.

These resolution figures are for the Mamiya 7, 80 mm and 150 mm supported on a ZONE VI tripod (indoors), with hot lights (500 watt quartz). Interestingly, the 150mm lens gives higher resolution at more apertures than the 80, in which diffraction starts reducing resolution between f 8 and f 11.

My Hasselblad with 80mm Planar topped out between 80-90 lines/mm, so it went on the market. A Fujica GSW690 was comparable to the M-7, with a little higher contrast.

According to Mr Sleicher's instruction sheets, the diffration limit of the aerial image is about 200 lines at f 8, and 150 lines at f 11. Diffraction at f 4 is 400 lines/mm, and I would expect a really top lens would achieve 140 lines _on film_ at this aperture, unless other distortions( spherical, lateral chromatic, astigmatism, etc) come into play at these wider apertures.

I would love to hear other's experience with this chart--please take out the .nospam in my Email address when you reply. TIA, good shooting to all.

[Ed. note: this letter from Mr. Sleicher may be of interest...]

Date: Sun, 31 Oct 99
From: Charles Sleicher [email protected]
To: Robert Monaghan [email protected]
Subject: your web site on lens testing

Dear Robert,

I have discovered your useful and informative web site belatedly, but I have a number of things to say about it. First of all, let me tell you that I am the designer of the Sleicher chart that David Jacobsen and Bob Atkins have refered to. By trade I am a chemical engineer, and I am retired from the University of Washington, where I taught for over 30 years. Since retirement I have been able to devote time to photography. I do mostly nature photography - wildlife and scenics. I have had modest commercial success as a stock photographer and seller of prints. My credits include the National Geographic, the Sierra Club Wildlife Calendar, Sunset Magazine, an Audubon calendar, winner of the 1998 Annual Photography contest in the wildlife division of Nature's Best magazine, local publications, and several exhibits.

About the table you attributed to David Swager - if I click on the link to Swager's resolution page, I get a page from a pamphlet by Brian Geyer of Really Right Stuff. The numbers in the table come from me. They appear in the instructions that I send out with my chart, and were used by Brian with my knowledge and support. I think it would be a good idea if you noted that this table is strictly empirical and subject to change if more or better data become available. Even better, you may wish to present my original table, which has an additional column for Technical Pan.

....I can send you one of my charts. The chart comes with (1) detailed instructions, (2) a set of targets designed for wide angle lenses, and (3) a slide of the chart that has targets that are resolved at 100 l/mm, which helps users to evaluate their microscope or other measuring equipment. I have received many complements on the clarity and completeness of the instructions.

--------

[Editor's note: you can reach Mr. Sleichert at:

Charles Sleicher
5002 Harold PL NE
Seattle Wa 98105

According to Mr. Terry Roth's posting above, the charts plus slide and 10 page manual are available for only $28 (US)...]

From: Gene Crumpler [email protected]
Subject: Response to lens test chart
Date: 1998-05-19

Terry;

I have not used the test chart you are using, but I have some experience with tech pan that might be of interest. I'm assumming you souped the 120 tech pan in technidol. I have been using ethol TEC with tech pan in 35mm for nearly 10 years and more recently in 120. I have found the following; TEC will give as fine or perhaps finer grain with both 2415 and 6415. More importantly, an EI of 80-100 is normal for 2415 and 6415 with TEC!! Also of interest, TEC will cost about 5-10 cents a roll versus 2-3$ for technodol. TEC in the 2 solution stock solution configuration will last 3-4 years with refrigeration, since you can develop 120 rolls of 120 and 200 rolls of 35mm with it.

Test of a new 55F4 pentax p67 lens also yields comparable results to your mamiya. In fact the resolution of that MF lens is comparable to my best nikkors. Japanese glass is as good or better than German.

From: frank a bridges [email protected]
Subject: Response to lens test chart
Date: 1998-05-19

That was a very interesting post. I have a question: Since color print film has considerably less ability to resolve than the film you were using, would it(color film) really reveal a difference between a lense that has 120 l/p/m and one that had 80-90 l/p/n. i seldom use b and w film. I've been told it was a waste of time to test lenses using color film because the resolving power of the film was only about 90 l/p/m at best. is this true?

From: Tim Brown [email protected]
Subject: Response to lens test chart
Date: 1998-05-19

Check out my lens testing efforts: http://db.photo.net/bboard/q-and-a-fetch-msg.tcl?msg_id=0005l3

[Namely:
One...more...time

Conditions: Film: Tech Pan Developer: Microphen diluted 1+5, 14 min @ 75 deg. F Illumination: Multi strobes, max duration 1/1000 sec. Magnification: 1:36 Lenses: All black, 55, 80, 105D, 135, 180 Super, 250 Body: C330, tripod, cable release Finder: Beattie Intenscreen w/ split prism, chimmney shade Target: Stepped target, stripes similar to USAF 1951 Neg viewer: Zeiss microscope 100X

Edge limits legend: T=blurred tangential lines R=blurred radial lines C=field curvature

F-stop, center lp/mm, edge lp/mm

55mm:
4.5--57---25TC
5.6--71---32TC
8----71---40T
11---71---40T
16---63---45T
22---57---40T

80mm:
2.8--50---28TF
4----57---36TF
5.6--63---32
8----90---40
11---90---50
16---71---40
22---57---36

105mm:
3.5--57---36R
5.6--71---40R
8----90---57
11---80---63
16---63---50
22---57---50

135mm:
4.5--45---32R
5.6--50---40
8----57---32
11---63---28
16---57---28
22---50---28

180mm:
4.5--71---40T
5.6--80---50T
8----80---45T
11---71---45
16---57---45
22---50---40

250mm:
6.3--63---45T
8----63---45T
11---71---45T

Asked by Tim Brown ([email protected]) on December 05, 1997.

[End posting]

I don't think 90lp/mm is a reason to dump a Hasselblad lens. My "worst" lens topped out at 63lp/mm but I've got some 11x14 prints from this lens that look damn sharp to me and others. To put it in perspective I printed the center section of one of my sharpest test negs (total image 30x30"). I couldn't see what was there beyond about 50lp/mm without looking at the print with a loupe. My best lens topped out at 71 lp/mm with Delta 100. I've learned that lens testing with visual targets is an iffy thing at best.

Date: Tue, 26 May 1998
From: JJMcF [email protected]
Subject: Re: [Rollei] Optically flat glass plate

In a message dated 98-05-26 15:58:49 EDT, you write:

If the plate is going to have any effect I would expect to see it more at the center of the image. Any buckling of the film will be greatest there. Supposedly, this thing was intended for use with the telephoto Rollei although it seems to me that the WA lens would be more critical. It also is unlikely to have a significant effect when photographing other than flat surfaces.

The Rollei film gate and guidance arrangement has always had a good reputation for good film flatness with roll film.

Recently I have been looking at film loaded into various cameras and rollfilm holders and it is shocking how un-flat rollfilm is at the film plane in most cases. Contrary to expectations, there is not always a bulge in the middle--sometimes the middle is the low point with various bulging around the edges. The biggest compromise for most rollfilm cameras is not allowing the film enough room to flatten out after turning a corner. (To do so would render the camera unduly large.) Thank heaven for depth of field.

John McFadden

rec.photo.equipment.large-format
From: "Richard Davis" [email protected]
[1] Re: Image Circles/Different Formats ??????
Date: Fri Jun 19 21:17:31 CDT 1998

The answers to the first two questions are straight forward, based on the difference between two things that even experienced photogs confuse--angle of coverage, and image circle. Those points were made very neatly in the other answers.

And there was a good discussion started in response to your last question.

When you start comparing formats--especially medium format vs large format--you step out of the tidy (relatively) world of physical optics and head straight for religion.

I want to support the excellent point that Arne Croell made about perspective--sure you can use the same lens with both formats, but if you move the camera you change perspective. The most dramatic evidence of this I see is in portraits, where a long lens for 2 1/4, like a 135mm, can make faces look clownish with exaggerated features when shot in 4x5.

But there are two other points that make me bump into things when I wander through Pro shops...

You can't generalize about the enlargability and image resolution of images in different formats when different films and lenses are involved. In fact a good friend who knows lots more about this stuff than I do says that with modern films and optics, you will not see improved resolution or optical goodness in large format when compared to medium format in at least 99.44% of the images you look at.

Part of the thinking behind this relates to your topic of image circle. In general it is easier to make a lens sharp if you don't need to make a large image circle--just ask the designers at Schneider. So even though you have more silver to play with on the larger format, some of that resolution may not be realized, simply because the lens may not be quite as sharp. But obviously there are exceptions to this rule, since the sharpness of modern lenses is pretty amazing. Part of the thinking behind this relates to your topic of image circle. In general it is easier to make a lens sharp if you don't need to make a large image circle--just ask the designers at Schneider. So even though you have more silver to play with on the larger format, some of that resolution may not be realized, simply because the lens may not be quite as sharp. But obviously there are exceptions to this rule, since the sharpness of modern lenses is pretty amazing.

The second point about the difference between medium and large format also relates closely to image circles. The point is about camera movements. The base note shows that the author knows about movements because of the comment that the camera needs to be zeroed to make the comparisons he is talking about. In the example of comparing 4x5 to 8x10, a crucial point is that the lens would be able to make much more extreme movements on the 4x5 than on the 8x10. So the image circle is large. In medium format, be it Rollei, 'Blad, or Bronica, there is no movement. So the image circle can be very small. But now we are back to the old argument that a lens with a large image circle probably can't be made quite as sharp. But with movements in large format with the big image circle, you have better control over depth of field, which is sometimes much more important than just sharpness. See what I mean about religion?

Where the same emulsion is used for both roll and sheet films the resolution is the same. Coating thickness is about the same on both types, its the support which is a lot thicker on sheet film. This is of no consequence for scattering or loss of resolution.

Some films do have thinner emulsions, Technical Pan, for example, but again, the emulsion thickness is the same regardless of the format.

Film has gotten good enough so there isn't a big jump in quality between 6cm x 6cm and 4x5 as there was in the past. There is still a big jump between 35mm and 6x6 but there used to be another just about as great when going to 4x5, no longer, at least for reasonable size prints. You can still see the difference for prints larger than about 11x14 its just not a stunning as it was many years ago.

---
Richard Knoppow
Los Angeles, Ca.
[email protected]

From: Kerry Thalmann [email protected]
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Resolution 6x7 cm vs. 4x5 inch
Date: Tue, 23 Jun 1998

Hi Peter,

I don't wish to argue, but I am curious as to what you think limits the enlargement factor to 3.5. Is it on-film resolution or visible grain? Based on the lens tests Chris Perez and I have been conducting, and several articles I have read on the subject (and practical experience) it would appear that on-film resolution would permit a much larger enlargement factor. Using a modern fine grained film (T-max 100 for black and white or Fuji Velvia for color) and the very best modern lens, you should be able to enlarge by a factor of 10 before the human eye can detect any loss of sharpness in the final print when viewed from 1/2 meter (a very close distance to view a 40"x50" print). This does not take into account the effect of visible grain in the final print. I have not yet determined what the limit is on enlargement before I find the grain distracting. Of course, this all depends on the film used, the viewing distance (if the print is otherwise sharp, the eye becomes much more forgiving of grain as the viewing distance is increased) and the eye of the viewer. One article I did read that compared the effects of both grain and on film resolution determined it was indeed the grain that limited the enlargement factor (to 2.75 based on his results) even though the on film resolution in his tests yeilded an enlargement factor greater than 9.

So, we keep hearing the argument that modern films and lenses are so good that there is no longer a need to shoot large format (of course, I don't buy into that argument, and it is always presented by those who shoot in smaller formats), but it indeed looks like we need even finer grained films to get a higher degree of enlargement. Modern lenses (and for that matter even many 50 year old large format lenses) are capable of achieving very high on-film resolutions. In the end, it looks like the grain structure of the film may be the limiting factor in determining the maximum enlargement. Of course, this grain structure is a function of the emulsion and will be the same for any emulsion regardless of the format.

Finally, the normal viewing distance increases as the size of the print increases. Grain that is objectionable in an 8"x10" print at 1/2 meter may be unnoticed in a 40"x50" viewed from across the room. This is the one relationship I have yet to quantify (I still need a formula for the effects of visible grain as a function of viewing distance). I have made prints up to 30"x40" from 4x5 with acceptable (for me) results, and I regularly make 24"x30" prints. This relationship between visible grain and viewing distance is one more factor that favors the larger formats. Assuming the same emulsions and a constant enlargement factor, the final print size, and thus the normal viewing distance increases as direct function of the film size. So, even though the enlargement factor is similar, at normal viewing distances, a 20"x24" print from a 4x5 original would appear less grainy than an 11"x14" print from 6x7cm. This also explains why, in a gallery setting, I can always tell from across the room, which 20"x24" prints were made from medium format and which from large format. It is not the lack of sharpness of the film or lenses, it is simply the effects of the film grain. The grain is just much more obvious, to my eye, in the prints made from medium format originals.

Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://home.att.net/~k.thalmann/

From: [email protected] (Richard Knoppow)
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Resolution 6x7 cm vs. 4x5 inch
Date: Tue, 23 Jun 1998

There are a number of conflicting, or at least not very intuitive, factors here.

First, the resolution of the system is going to be considerably less than the resolution of either film or lens. At least in medium format and small format the resolutions of film and lens will be somewhat similar. When lens and film have equal resolution the resulting system resolution is either 1/2 or 2^1/2, depending on how you calculate it.

The resolution numbers being stated here are all high-contrast numbers (1000:1). Resolution of both film and lenses varies with contrast. In film, its due to scattering and some other factors, in lenses its due to residual spherical aberration and other aberrations.

For low-contrast targets, perhaps 10:1, resolution numbers for both film and lenses will be much lower, perhaps half the high-contrast numbers.

Adding to this the loss in enlarging, which is not straight forward to calculate, results in a surprizingly low number by the time the image gets to the paper.

Larger formats to some degree reduce the contribution of both the film and the printing process to this degradation of resolution. The lenses may have less resolution due both to greater residual aberration in most large-format lenses (may not be true of the very latest crop) and to the necessity of stopping down for reasonable depth of field.

Larger negatives also have the advantage of more grains to carry the image so have better tonal reproduction than smaller ones. This is very apparent when comparing 35mm to anything larger but less so when the smaller is larger than 35mm.

Perceived sharpness is controlled more by other factors than resolution. Edge contrast is an important one. The eye also tends to interpret contrast as sharpness, even when the actual detail reproduced is poor.

There is probably an optimum size negative for a given print size, it will be different for different film and perhaps also other factors. I have no idea how to calculate such a thing but visual examination gives some clues.

---
Richard Knoppow
Los Angeles, Ca.
[email protected]

From: "Christopher M. Perez" [email protected]
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Resolution 6x7 cm vs. 4x5 inch
Date: Tue, 23 Jun 1998

John wrote:

> Sometimes I get asked how
> much better [4x5] is than medium format 6x7 cm.
>
> 1. 4x5" is x % bigger than 6x7 cm. Does it contain equally much
> information?

4x5inches gives 20 square inches of surface area.

6x7cm gives 6.5 square inches of surface area.

You get _three_ times the surface area by using 4x5. I'd say you get significantly greater information on film by using 4x5.

> 2. Some say that MF film is better because it is thinner and has less
> diffraction - what are the actual datas describing this phenomena?

I've not found any and would be v.interested if someone could come up with a pointer to this information.

> 3. What is the accepted usable surfaces on each resp. film?

See first comment.

> 4. Are there any sites that show real tests and comparisons between the two
> formats... One often heard comment is, "well, medium format is quite good
now,
> the
> films have become so much better....". Hasn't film on 4x5" got equally much
> better?
>

We know that the best film will resolve in a 1:6 contrast ratio image is right at 100 lines/mm. This holds true regardless of whether it's 120/220 (thin-base film) or 4x5. I understand that this holds true between certain color films and the latest fine-grain B&W. So, no, there will be v.little or no difference between the two (thin or thick-base) film's ability to resolve.

Kerry Thalmann and I have been testing various lenses (and I will be testing a few 6x6/6x9 lenses in the near future). You can see the latest results at: http://www.hevanet.com/cperez/testing.html I am making a short leap of faith in saying: You will find no practical difference between a well made lens for use in 4x5 or 6x6/6x7/6x9. The primary difference being the compromises required to fit a mirror between a lens and the film as needed by many 6x6/6x7/6x9 cameras these days. This may well influence the quality of lenses in medium format (tilting in favor of well-corrected 4x5 lenses! - see my comments on the practical results seen in testing Schneider's new lens designs at: http://www/hevanet.com/cperez/kit.html ).

The "real" differences between these formats may well end up being just how much more magnification is required to enlarge 6x7 to the same final print size. The grain structure of an enlarged 6x7 image will be at least _twice_ the size of a 4x5 image printed to same final print size!!!

Only you will be able to tell us if this difference is important or not.

Personally: I'd suggest shooting 8x10 transparencies and just call it a day... the quality _is_ visible... :-)

- Chris

rec.photo.equipment.large-format
From: [email protected] (Thor Lancelot Simon)
[1] Re: Resolution 6x7 cm vs. 4x5 inch
Date: Sat Jun 27 00:14:53 CDT 1998

Kerry Thalmann  [email protected] wrote:
>P.Groepper wrote:
>
>> One may argue about the mag.factor of 3.5, but I don't care to much
>> about such details. Anything wrong with this approach?
>
>Hi Peter,
>
>I don't wish to argue, but I am curious as to what you think limits the
>enlargement factor to 3.5.  Is it on-film resolution or visible grain?
>Based on the lens tests Chris Perez and I have been conducting, and
>several articles I have read on the subject (and practical experience)
>it would appear that on-film resolution would permit a much larger
>enlargement factor.

Yeah, *but*:

Who uses glass negative carriers consistently? Bob Salomon and I argued viciously about this years ago and he was, frankly, right. Experimentation finally proved to me that negative flatness was far and away the limiting factor in the sharpness of my prints from large-format film. This is a much more severe problem for sheet film than for small roll film.

I hate glass carriers. I just can't keep the things clean, I get newton rings, and all the other problems. I've compromised on a Negaflat; if I ever get an 8x10 enlarger I guess I'll grit my teeth and bear the hassle, though.

Also, many people's enlargers are quite poorly aligned, often front-to-back which is generally a bit harder to adjust precisely than side-to-side, without a vacuum easel the paper's never totally flat (much less of an issue than film flatness however), and few darkrooms are constructed with proper care to isolating the enlarging bench from fan vibration.

To top it all off, because of the various flatness and focus issues, 4x5 is generally enlarged at significantly smaller apertures than 6x7 or 35mm, so the enlarging lens is generally diffraction-limited which again reduces the theoretical resolution of the end-to-end system, if it were otherwise perfect, which it is not.

--
Thor Lancelot Simon
[email protected]
"And where do all these highways go, now that we are free?"

Date: Sun, 28 Jun 1998
From: Edward Meyers [email protected]
Subject: Re: [Rollei] schneider versus Zeiss 6008i lenses

I have not tested the following with the 6008, but the follwing may be of interest to many of you...

One fact which I didn't mention, but one which I hinted at, which is many times the major image sharpness factor, is film flatness. the Hasselblad film magazine, in the past, was one of the biggest contributors to unsharpness, even when imaged with the fine Zeiss lenses. The TLR Rolleiflex didn't suffer from this illness. Film in the Hasselbald magazine takes an abrupt bend before it reaches the section where it is exposed to make a photograph. If you load the film and shoot some pictures--no problem. But if you shoot a few frames and then leave the film in the magazine for a while--then shoot pictures, there's a good possibility that the next frame will not be flat during exposure time. It may have a "bump" in it, so focus of objects will not be consistant. The TLR Rollei's film bend is not so abrupt.

Another problem with rollfilm imagery is that the film in the beginning of a roll can lay flat. Film of the last few exposures come from closer to the film spool core, and therefore often show slight bumps, which can result in erratic sharpness within the 6x6cm negative. Just take an old roll of 120 film and open it up. Hold it at an angle to some light and compare emulsion flatness of the beginning of a roll and the end of a roll. Not the same. This is one major reason why 620 film died. The spool was much thinner in the center and this difference was greater. 127 suffers in a similar manner.

So, in evaluating lenses evaluate the system--camera and lenses, and make actual photographs on film. This is my opinion.

Ed Meyers

rec.photo.equipment.large-format
From: Kerry Thalmann [email protected].
[1] Re: RESOLUTION 120-film vs 4x5 SHEET FILM
Date: Thu Jul 09 13:07:40 CDT 1998

Christopher M. Perez wrote:
>
> Please review the lens tests from the '70's and '80's as published in Modern
> Photography.  Rarely, and I mean very rarely, did a lens ever test better than 100
> lines/mm.  They must have used a slow film as today's TMax100 will resolve between
> 100 and 120 lines/mm depending upon the contrast of the scene (1:6 is pretty
> standard).  Most of the lenses tested by MP between f/5.6 and f/11 (typical working
> aperatures for 35mm photography) resolved around 60 to 80 lines/mm. Sometimes you'd
> see 90 lines/mm and they'd be falling all over themselves in explaining how great a
> lens it was.
>
> Guess what:  Large format lenses can resolve this well at f/11 to f/22 (typical
> working aperature for 4x5)!  And it'd be pretty interesting to see how well a 75mm
> Boigon would perform at the wider aperatures (yes, this is a specialized, not
> general, case).
>
> The theoretical resolving power of lenses who's f-numbers are 5.6 is around 246
> lines/mm.  But no film shot in a 1:6 contrast ratio setting can resolve this. And no
> aerial inspection for lens quality has been able to prove makers of 35mm lenses can
> come anywhere close to this.  Something about manufacturing tolerances.
>
> Therefore I would challenge the assertion that 35mm lenses are "way sharper" than 4x5
> lenses.  Now the original topic compared lenses made for 6x6 applications against 4x5
> lenses.  I believe many similar things can be shown for the differences between these
> lenses as well.  I have some lenses I will be testing to see how well this argument
> hangs together later this fall.

I agree in principal with everything Chris said. However, I have seen very high aerial resolution numbers published for the best modern 35mm lenses at wide apertures. I have seen numbers as high as 360 lpmm at f4 and 265mm at f5.6. These are actual measured values, not theoretical maximums. Of course, the 265 lpmm number violates Chris' theoretical maximum of 246 lpmm, but diffraction is a function of the wavelength of light, and I don't know the details of the lightining used for the above measurements. BTW, the article I am referencing is: "Resolution ... what you get" by Brian Guyer (of Really Right Stuff). His numbers reference the work of others based on the measurement techniques of Charles Sleicher. In the article he lists the theoretical, diffraction limited resolutions of 400 lpmm at f4 and 300 lpmm at f5.6. So, according to this article,the best modern 35mm lenses are capable of performing at about 90% of the theoretcial diffraction limited resolution at wide stops WHEN MEASURING THE AERIAL IMAGE RESOLUTION.

The last statement is where Chris is right on the money. On film resolution is a combination of the performance and the capabilities of the film. It will be less than the worse of the two, and as Chris mentioned is a function of subject contrast. In other words, for modern 35 glass at wide stops, it is the film limiting the resolution, not the lens. Just for completeness, here's the other numbers Brian Guyer sites in his article (again these results are stated for "numerous top quality 35mm lenses")

f-stop  aerial resolution       theoretical max.
f8      180 lpmm                200 lpmm
f11     130 lppm                150 lppm
f16     90 lppm                 100 lppm
f22     65 lppm                 75 lppm

Now, let's talk about on-film resolution. This is where Brian Guyer loses me (my fault, not his). He states that film resolution is also a function of aperture. Specifically, he states:

"However, film resolution has also been shown to vary appreciably with aperture, and resolving power is always highest when the light source area is minimized, to retard dispersion. This presents a troubled dichotomy: Best lens resolution is achieved when shooting wide open, but best film resolution is at ~ f22 (or smaller)!"

Unfortunately, he does not give a specific formula or measured data for the different film resolutions at different apertures. He does site a source that might help me understand what he is describing. That source is: "Image Clarity" by John B. Williams. I requested a copy via inter-library loan from my local public library about two weeks ago, but have not yet received it. At this point, I neither agree, nor disagree with Brian Guyer's statement and resulting conclusions, I would just like to understand it more before reaching any conclusions of my own.

He does conclude with a table showing the resulting combined lens/film resolutions from f2.8 to f22. This table assumes ideal, diffraction limited lenses (not the actual measured aerial resolution numbers sited in his previous table), and a film capable of resolving 120 lpmm (of course, there are few if any films capable of 120 lpmm for subjects of "normal contrast, but since most measurements use test charts of fairly high resolution, I am willing to accept the 120 lpmm for test charts and scale down for normal subjects of lower contrast).

Here's his final table (assuming ideal, diffraction limied lenses):

f-stop  combined lens/film resolution   theoretical max. lens resolution
f2.8            80 lpmm                         600 lpmm
f4              90 lpmm                         400 lpmm
f5.6            95 lpmm                         300 lpmm
f8              100 lpmm                        200 lpmm
f11             95 lpmm                         150 lpmm
f16             80 lpmm                         100 lpmm
f22             70 lpmm                         75 lpmm

So, even assuming an ideal diffraction limited lens combined with a high contrast subject and a film capable of 120 lpmm, he concludes the best possible on film resolution will be 100 lpmm at f8 (BTW, this conculsion is independent of film format, since he is using theoretical, diffraction limited lenses). Again these are his conclusions, and I am merely quoting them here (under "fair use"). For copyright reasons, I have not copied the entire article. Also, like I said above, I don't fully understand the relationship between aperture and film resolving power. Although I don't dispute his numbers in anyway, I would like to understand their derivation better.

Anyway, this agrees very well with what Chris said about the test reports in Modern Photography. Basically, that 100 lpmm was about the best they could do, and 90 lpmm was enough to get real excited about.

Now, here's the real kicker. I am always hearing people make the statement that 35mm (or medium format) lenses are SO MUCH SHARPER than large format lenses. That may be true for aerial resolution on a test bench (or it may not be, I haven't seen enough aerial resolution numbers for the best modern large format lenses at wide apertures to know). Anyway, with the best modern large format lenses, it may still be the film that is limiting the resolution, not the lens. For example, in the on-film large format lens tests Chris and I have performed, we have seen numbers as high as 85 lpmm at f11, 80 lpmm at f16 and 68 lpmm at f22. These are the measured resolutions near the center and mid-point of a 4x5 negative. If we go all the way to the corners, we see up to: 60 lpmm at f11, 67 lpmm at f16 and 61 lpmm at f22. In his article, Brian Guyer did not mention if the numbers he quoted were for the center of the field, or the corners of a 35mm negative. Even if they are for the center, I am willing to believe there will not be a huge degradation in the corners due to the small image circle requirements of 35mm (although is could be significant for even the best of the modern 35mm ultrawide angle lenses). So, even if 35mm lenses are much better in theory, on film the differences between the best 35mm lenses and the best 4x5 lenses are not that great.

Keep in mind, that due to the smaller negative size of the 35mm format, you need to divide the 35mm on-film resolution numbers by 4 to get the resolution required of a 4x5 lens for the same on-print resolution for prints of equal size. In other words, a large format lens capable of delivering 25 lpmm on film, will be the equal to, in final print sharpness, the best 35mm lens (using Brian Guyer's 100 lpmm maximum for an ideal diffraction limited lens). If you review the test results Chris has posted, all but the very worst of the large format lenses we have tested are capable of resolving 25 lpmm on film. The ones that fail, are usually older wide angles at the corners at wide apertures. Many of them exceed 25 lpmm when stopped down to normal working apertures. A couple of the really poor performers have obvious defects (separation in one of the 90mm Angulons for example - keep in mind many of these older lenses are 40 - 60 years old). Of course, the best of the modern 4x5 lenses (and several of the older ones, as well) far exceed 25 lpmm, even in the corners, even at their "worst" aperture. For example, look at the 110mm Super Symmar XL at f16, it is capable of resolving, on film, 67 lpmm across the entire 4x5 field. You'd need an on-film resolution of 268 lpmm from a 35mm negative to get equivalent sharpness in the final print. Although the best of the current 35mm lenses may be capable of such a high resolution at some apertures, they will be not be capable of producing anywhere near such results on film due to the limitations of currently available films.

Of course, in the end, the on-print resolution will be a function of the on-film resolution, degree of enlargement, the imperfections of the enlarging system (greater for 35mm, due to the greater degree of enlargement), the resolving limits of the printing paper, and the ability of the human eye. Still, I conclude that the statement that "35mm lenses are much sharper than 4x5 lenses" may be true for aerial images at wide apertures examined with a microscope, but it is definately not true for on-film resolution - where it counts (I'd agree with the above statement if you changed "much sharper" to "slightly sharper"). Actually, where it counts even more - in the final print, the best 4x5 lenses will easily blow away the best 35mm lenses. This is even true for the best of the 40 - 60 year old 4x5 lenses we have tested. And all but the very worst of the older 4x5 lenses, shot at their worst f-stops, will be equal, or better in final print resolution to the very best achievable with modern 35mm equipment (due to film limitations) for equivalent sized final prints.

Of course, we are only talking resolution here. At some point,for me personally, visible grain starts to detract from the quality of the final print. All the more reason to prefer large format over 35mm.

Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://home.att.net/~k.thalmann/

rec.photo.equipment.large-format
From: [email protected] (CWood 7000)
[1] Re: RESOLUTION 120-film vs 4x5 SHEET FILM
Date: Thu Jul 09 18:27:31 CDT 1998

I have seen the same argument presented in the past in a magazine, the editor replied the F/22 and higher defraction argument is not valid as large format lenses have a longer focal length than 35mm optics for an equivlent angle of view and therefore, are much likely to cause loss of sharpness due to diffraction.

rec.photo.equipment.large-format
From: [email protected] (Richard Knoppow)
[1] Re: RESOLUTION 120-film vs 4x5 SHEET FILM
Date: Fri Jul 10 03:49:39 CDT 1998

[snip - removed quote of above post]

This is a lot of stuff to leave quoted but I can't figure out what could be snipped without loosing context.

One must be careful in quoting diffraction limits. First, they vary with wavelength and are usually stated for a specific wavelength of monochromatic light. The resolution numbers for white light are significantly lower than for monochromatic light. The chart which Chris Perez has (source moi) is calculated for 589.3mu, which is midway between the Sodium D lines (yellow) about the center of the visible spectrum.

The values stated in the middle chart above seem to be for light at the blue end of the spectrum and are too high.

Secondly, the diffraction limit depends on the angle from the optical axis. The values fall off notably as the angle is increased becoming about half the center value at a 40 deg half-angle.

Also, when off axis, the resolution limit is different for radial lines and Tangential lines. The reason is obvious if one observes the shape of the stop at an angle. It becomes football (American bootball that is)shaped, so has effectively a larger aperture for one direction.

Actual resolution also depends a _lot_ on how well the lens aberrations are corrected. The diffraction limit of the stop is the absolute limit any lens can have. Real world lenses typically have much lower resolution for any stop except the smallest where the diffraction limit becomes very low.

It should also be noted that the examination of aerial images is subject to a number of potentially serious errors. The lens or lens system being used to examine the image can act as a stop and give a false indication, resulting in higher resolution than is actually the case. Also, when working near the limit some test targets can give fase indications. The number of bars or lines must be counted carefully. It is possible to get what looks like separated lines when it is only an overlapping of the diffraction pattern. When this happens the number of bars or lines in the target will be smaller than the actual number.

Further, lens resolution will depend on target contrast. The contrastier the target the higher the resolution will be. This is a result of uncorrected aberrations, mainly spherical and coma, but others contribute, which acts somwhat like flare. This effect can be seen on MTF curves.

As an after note. It is possible to make special purpose lenses with very high performance. Kingslake describes such a lens designed by Kodak for use in its labs in measuring film resolution. This lens is f/2 and has 500 l/mm resolution at the center of the field. It is designed and used with _monochromatic_ light and covers a very narrow field (I think 20deg) at a specific distance. No white light general purpose lens would get even close to this.

I am also skeptical of anyone who claims to get very high resolution on film. If you can get an actual 60 l/mm you are doing very well. Anyone who claims stuff like 200 lpm is either using a Lippman emulsion and monochromatic light or pulling the wool over your eyes (maybe with the sheep still attached).

The measurements you and Chris have come up with seem to be quite reasonable and are probably good valid measurements. I am _very_ skeptical of magazine articles, especially those of the sixties and seventies.

---
Richard Knoppow
Los Angeles, Ca.
[email protected]

From: steven T koontz [email protected]
Newsgroups: rec.photo.equipment.large-format
Subject: Re: RESOLUTION 120-film vs 4x5 SHEET FILM - comments please
Date: Thu, 09 Jul 1998

> > . if you compare a > > 24mmX36mm crop of a 4X5 neg and compare it to a 35mm neg (shot with > > 35mm lens) the 35mm neg with be much better..but the sharper 35mm lens > > won't even begine to cover 4X5.. > > No. If you take a 35mm lens, shoot it at f/16 or f/22 and compare it against a > 4x5 lens shot at the same aperature you will see no difference. The lenses will > resolve equally. The limits of diffraction will restrict resolution to 81 > lines/mm and 61 lines/mm (approx.). >

but you almost never shoot a 35mm at f22. Most shots are done at f5.6 to f8 where the lens is way sharper than a 4X5 lens..And I only use f11 on my fuji as that is the sharpest aperature while a LF one is ussually f16-f22 (to get corners sharp). Sure at f22 my fuji lens is dead (as are most 35mm ones) but no one uses those aperatures because of this... with a 4X5 you have to... reason the smaller format lenses aren't difraction limited is you don't have to shoot them at f22 to get them to cover the fromat sharply.. lets use real world examples to compare this stuff..

--

steve's photography & Z car stuff
@ http://www.mindspring.com/~skoontz
[email protected]

Date: Tue, 07 Jul 1998
From: "David W. Richardson" [email protected]
Reply to: [email protected]
To: Robert Monaghan [email protected]
Subject: Re: 2400 dpi < 50 lpmm resolution? Re: RESOLUTION when scanning

Robert Monaghan wrote:

> First order would be maximum one dot black line one dot white space for
> maximum 1200 lines per inch, yielding the maximum density of lines,

First, film is measured in line-pairs-per-inch (or mm), not lines-per.

Cut 2400 in half to get line-pairs, then cut that in half, to 600 line pairs per inch, due to the the Rhynquest (spelling?) frequency (see any technical book on analog-digital conversion for more info on this).

Here's why the 2nd cut-in-half:

In the table below, /--\ represents one pixel of the scanner, "****" is a black  
area on the paper, and "...." is a white area on the paper.  Here's a 
1/600 (4-pixel) example:

/--\/--\/--\/--\/--\/--\/--\    - total length at 2400 dpi:  1/600 inch
****    ****    ****    ****    - 1200 line pairs per inch, reads OK *IF*
                                  aligned perfectly.

BUT if the lines are offset, you can't see 1200 lp/in, only 600:

/--\/--\/--\/--\/--\/--\/--\    - total length at 2400 dpi:  1/600 inch
  ****    ****    ****    ****  - 1200 line pairs per inch reads as grey
                                  (or, with a 1-bit scanner, as either
                                  solid white or solid black)

/--\/--\/--\/--\/--\/--\/--\    - total length at 2400 dpi:  1/600 inch
  ********        ********      - 600 line pairs per inch reads as    
                                  grey-black-grey-white-grey-black-grey,
                                  which is OK as you are going to get.

The rest of your calculations are good (but off by a factor of 2).
> right? And at 25.4 mm per inch 1200 lines/inch /25.4 mm/inch = 48 lines/mm 24 lp/mm. 

Most lenses/films are about 80-160 lp/mm, so you will need to scan at about 10-20,000 dpi to get a "perfect" scan. Drum scanners are the closest generally available technology we have now. My local pro lab drum-scans for $40-$60 depending on the total megabytes (more for very large scans). At that price, I'd recommend sticking with a flatbed or dedicated negative scanner for all but the most critical applications. At $40, we aren't yet to the point where we can throw away our negatives. Also, 35mm film would be 150 million pixels uncompressed (almost 0.6Gb, or a full CD-ROM). Imagine loading that into Photoshop.

Depending on what you are doing, dynamic range (a factor of the scanning hardware, the internal bits-per-pixel, and the external bits-per-pixel) may be more important. You almost always want at least 3, but sometimes need 4 or more. 30-bit (10 bits per color) scanners are generally about a DR of 3.0 or so.

--
-David W. davidwr@ Make your web pages accessible to the
Richardson geocities.com handicapped: http://www.cast.org/bobby

rec.photo.equipment.large-format
From: Kerry Thalmann [email protected]
[1] Re: RESOLUTION 120-film vs 4x5 SHEET FILM
Date: Mon Jul 13 11:49:40 CDT 1998
To: [email protected]

Richard Knoppow wrote:

>  This is a lot of stuff to leave quoted but I can't figure out what
> could be snipped without loosing context.

Hi Richard,

Thanks for the response. I decided not to re-quote my original article (it was rather long and has already been posted twice). If anybody hasn't seen it yet, it's archived on Dejanews.

>   One must be careful in quoting diffraction limits.  First, they vary
> with wavelength and are usually stated for a specific wavelength of
> monochromatic light. The resolution numbers for white light are
> significantly lower than for monochromatic light.  The chart which
> Chris Perez has (source moi) is calculated for 589.3mu, which is
> midway between the Sodium D lines (yellow) about the center of the
> visible spectrum.
>  The values stated in the middle chart above seem to be for light at
> the blue end of the spectrum and are too high.

I did briefly mention that diffraction was a function of the wavelength of the light source, but I didn't go into any depth. Thanks for filling in the details.

>   Secondly, the diffraction limit depends on the angle from the
> optical axis.  The values fall off notably as the angle is increased
> becoming about half the center value at a 40 deg half-angle.
>   Also, when off axis, the resolution limit is different for radial
> lines and Tangential lines. The reason is obvious if one observes the
> shape of the stop at an angle.  It becomes football (American bootball
> that is)shaped, so has effectively a larger aperture for one
> direction.

This is an area that I only hinted at, and explains (partially) why the ultrawide angle lenses generally have lower resolution in the corners than the normal and long focal lengths for any given format. The required half-angles for full coverage of the film area are much greater, and therefore, diffraction comes into play in the corners at much wider apertures. Again, thanks for filling in the details.

>   Actual resolution also depends a _lot_ on how well the lens
> aberrations are corrected. The diffraction limit of the stop is the
> absolute limit any lens can have. Real world lenses typically have
> much lower resolution for any stop except the smallest where the
> diffraction limit becomes very low.

I will respectfully disagree a little bit here. Obviously, the diffraction limit is the best case upper limit. Where I disagree is your last statement. The best modern lenses (regardless of format), are capable of performance NEAR the diffraction limits at moderate, or even fairly wide apertures. In other words, for the best modern lenses, diffraction starts to comes into play much at much wider apertures than with most older lenses. Early in our tests we were shooting our large format lenses at f16, f22 and f32 (typical working stops - for us). We quickly learned that most decent lenses (meaning any that weren't really poor, or damaged) performed nearly the same at f32 (pretty much within the bounds of experimental error). Most of the lenses we tested had marked apertures down to at least f45, many down to f64 and a few beyond. We decided it was pointless to test at such small stops, due specifically to the diffraction limits. Based on our tests at f32, we concluded all the lenses would perform equally due to diffraction at such small stops. We even abandoned testing at f32, and opted for f11, f16 and f22 for all further tests (except for some long lenses that had max. apertures in the f11 - f12.5 range). Many of the best modern lenses performed their best overall at f16, and if you only look at the middle part of the image, many were best at f11. At f11, in the best cases, we were starting to push the limits of the film. We didn't test any wider than f11, but I would be surprised if the very best of the modern lenses didn't perform even better at f8, and possibly f5.6 (in the center of the field). Theoretically, a perfect lens should be sharpest wide open. Of course, in the real world aberrations not fully corrected meant that the theoretical limits were never close to reached - until recently. There is still no such thing as a perfect lens, but I do think the very best of the modern lenses are coming a lot closer, and for these lenses, diffraction limits are approached at wider apertures. Of course, we may be in agreement here, but just have different defintions of "much lower" and "any stop except the smallest" in your statement: "Real world lenses typically have much lower resolution for any stop except the smallest where the diffraction limit becomes very low." Also, this all may be moot for most people unless they regulary shoot at wide stops (I personally usually shoot at f22 plus or minus one stop depending on subject and conditions). I occasionally shoot as wide as f11, but only for subjects that are relatively two dimensional (due to depth of field problems with complex, three dimensional subjects).

>   It should also be noted that the examination of aerial images is
> subject to a number of potentially serious errors.  The lens or lens
> system being used to examine the image can act as a stop and give a
> false indication, resulting in higher resolution than is actually the
> case. Also, when working near the limit some test targets can give
> fase indications.  The number of bars or lines must be counted
> carefully.  It is possible to get what looks like separated lines when
> it is only an overlapping of the diffraction pattern.  When this
> happens the number of bars or lines in the target will be smaller than
> the actual number.
>   Further, lens resolution will depend on target contrast. The
> contrastier the target the higher the resolution will be.  This is a
> result of uncorrected aberrations, mainly spherical and coma, but
> others contribute, which acts somwhat like flare. This effect can be
> seen on MTF curves.
>   As an after note.  It is possible to make special purpose lenses
> with very high performance. Kingslake describes such a lens designed
> by Kodak for use in its labs in measuring film resolution. This lens
> is f/2 and has 500 l/mm resolution at the center of the field.  It is
> designed and used with _monochromatic_ light and covers a very narrow
> field (I think 20deg) at a specific distance.  No white light general
> purpose lens would get even close to this.
>   I am also skeptical of anyone who claims to get very high resolution
> on film.  If you can get an actual 60 l/mm you are doing very well.
> Anyone who claims stuff like 200 lpm is either using a Lippman
> emulsion and monochromatic light or pulling the wool over your eyes
> (maybe with the sheep still attached).

I agree with you completely on these points. I don't totally discount the aerial resolution numbers that are being quoted, but I don't accept them as actual attainable values. They are really only useful for relative comparisons of different lenses (and as such, are valuable). I think they are tackling the "highest achieveable resolution" problem from the opposite end that Kodak did with their wonder lens. Kodak was attempting to achieve the highest possible film resolution numbers by eliminating the lens as a source of degradation, and optimizing the light source and contrast of the target. If you swap the terms "film" amd lens" in the above statement, you basically describe the test set-up used by those achieving the very high aerial resolution numbers. Still as long as the experiments are controlled and repeatable, you can get a good idea of relative lens performance using such test results. Just don't expect to ever come close to achiving those kinds of numbers on film, with a typical subject under natural light.

>   The measurements you and Chris have come up with seem to be quite
> reasonable and are probably good valid measurements.

In actuality, we are testing a SYSTEM with several different lenses, not just the lenses independent of other factors. In other words, in the real world, we shoot with the lens mounted on a camera, with film in a holder, so that is what we are testing. Again, this is not perfect (we are still using a test chart, not a "real world" subject), but it comes much closer to what we actually use these lenses for. As with the aerial resolution numbers, this is still a relative measurement. Unless somebody else is using the exact same camera, film, film holders, etc. as us, their results will probably not be exactly the same (however, the relative performance should be the same for the same lenses we tested). We started these tests with the goal of "cherry picking" the best possible compact wide angles for our own personal use, so all we were really interested in was relative measurements. Of course, our little project grew quite a bit since we originally conceived it, but we never changed our test methodology, and we also have never changed our position that our results are not absolute. In fact, as a result of our experience, we are even more adamant on that point than ever. We have learned that it is VERY important to test individual lenses. This is especially true when buying used and buying older lenses, but even for modern lenses there can be significant sample to sample variations. I can not stress enough that our results are only valid for the EXACT lenses we tested. Our results can be used as guidelines, but I do not recommend generalizing too much from our results. Our sample sizes were very small (in most cases we tested a single sample) and should not be considered representative of all lenses of any given design or brand. WE HIGHLY RECOMMEND THAT ANYBODY CONCERNED ABOUT THE PERFORMANCE OF THEIR LENSES DO THEIR OWN TESTS. After all, testing four or five lenses isn't too time consuming, and it is the only way to know how well YOUR lenses perform in YOUR system.

Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://home.att.net/~k.thalmann/

From: [email protected] Richard Knoppow
Newsgroups: rec.photo.equipment.large-format
Subject: Re: RESOLUTION 120-film vs 4x5 SHEET FILM - comments please
Date: Sun, 26 Jul 1998

[email protected] Type4Harry wrote:

>John,
>The thicker the film the more stable the image be, and the thicker the  emulsion
>the better it holds the opaquecity (I hope I spell it right), but  of course the
>grain of the emulsion is another factor to consider.
>
>Harry

I am not sure of what you mean by "stable". If its dimensional stability it depends on material rather than thickness.

Thicker emulsions suffer more from irradiation, that is, scattering of light, which tends to _reduce_ their resolution and acutance. The trend in modern films has been toward thinner emulsions and single coating. Obtaining adequate density (opacity) of the silver is one reason for T-grain and other "core-shell" type emulsions. The silver crystals are made to grow epitaxially so that they form "flakes" which have more area of coverage than normal crystals. As a result, emulsions of this type can be thinner for a given maximum density. They usually have better resolution than conventional types.

Sheet film is made on a thicker base than roll film mainly to make the film stay flat in the usual types of holders used. The emulsion thickness is the same, regardless of the support thickness.

The invidual emulsion layers of color films are very thin compared to most B&W films. They have to be in order to be transparent enough not to cause the image to become blured due to the scattering mentioned above.

The performance of an emulsion will be the same regardless of the support it is coated on. Large format versions of films have exactly the same sharpness characteristics as equivalent small films but have more area. The resulting image sharpness for large format may have less to do with the resolution capability of the film than other factors.

---
Richard Knoppow
Los Angeles, Ca.
[email protected]

From: "Christopher M. Perez" [email protected]
Subject: System testing madness - Continued
Date: Mon, 03 Aug 1998

There's been a bit of conversation regarding Medium Format vs Large Format vs image sharpness vs lens performance here in r.p.e.large-format. A couple things have been repeatedly noted:

- Large Format lenses from certain manufactures are quite outstanding

- TMax100 and several color films have a resolution limit of around 100 to 120lines/mm at 1:6 contrast ratio (regardless, it must be pointed out, of the film's backing)

Several people have questioned these findings by indicating that 35mm systems and Medium Format systems are "much sharper". Therefore, the contention appears to be argued, similar results to 4x5 work can be achieved in shooting MF (though no one has indicated that 35mm _really_ is capable of this... at least not yet :-).

I wanted to test these kind of statements by shooting 6x6 using TMax100 against my resolution target. The initial results are found here: http://www.hevanet.com/cperez/MF_testing.html

In particular, the Mamiya 80mm lens on the C220 Pro is a very fine lens. It has 5 f-stops where the center resolves 60 lines/mm or better. But the results are _not_ significantly better than an equivalent LF lens (see: http://www.hevanet.com/cperez/testing.html ). Taking this _single_ data point and expanding to many conclusions to include the "typical" MF system is risky.

Therefore, should anyone living in the Portland, Oregon area have a Hassy/Bronica/Fuji or other "really hot" system that they'd allow me to test, please contact the under-signed. I'm curious to see if a MF system can get much better than the Mamiya I tested (besides, I need a few more data points before I go shooting off my mouth and make some truely outragious claims :-).

- Chris

From: [email protected] (NYCFoto)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: System testing madness - Continued
Date: 3 Aug 1998

- TMax100 and several color films have a resolution limit of around 100 to 120lines/mm at 1:6 contrast ratio

According to the kodak dataguide book, the resolution for Tmax 100 is 200 ( i'm not certain if this is lines/mm) 320 for techpan, 100 for tri-x and 120 for t-max 400.

Several people have questioned these findings by indicating that 35mm systems and Medium Format systems are "much sharper". Therefore, the contention appears to be argued, similar results to 4x5 work can be achieved in shooting MF (though no one has indicated that 35mm _really_ is capable of this... at least not yet :-).

I shoot LF far more than I shoot MF and my opinion is as follows. I think that at a given degree of magification a lens designed for 35mm or MF ( and I'm talking top quality lenses for these formats, not amatuer stuff) will be optically superior to LF lenses for a simple reason. LF lenses are designed to have greater film coverage since they need to take into account coverage for camera movements. That is a big compromise on lens design compared to having to design a lens that barely covers a 6x6 or 35mm. However I think that a 4x5 shot with t-max 100 and made into a 20x24 print will be clearly superior to a 6x6 shot with t-max and made into a 20x24 print. There's just too big a difference in the amount of magnification between making same size prints from 2 1/4 to 4x5 films with 2 1/4 requiring 2.22 times more enlargement to make the same size print. In comparing 6x6 to 6x7, a 6x6 cropped to a 6x7 proportioned rectangle would require only 1.16 times more magnification to make the same size print. In this case I think a better quality lens on the 6x6 might nullify the film size advantage of the 6x7.

From: [email protected] (Richard Knoppow)
Newsgroups: rec.photo.equipment.large-format
Subject: Re: RESOLUTION 120-film vs 4x5 SHEET FILM
Date: Tue, 07 Jul 1998

"Karl Wolz" [email protected] wrote:

>Hi John,
>It sure seems that the folks in this newsgroup are beating you up a lot over
>nothing.
>
>The one thing I think you may want to try to give yourself some further
>enlightenment on this issue, is to duplicate the experiment with a couple
>other films, most especially with transparency films such as Velvia or EPP.
>
>I have noticed when using some transparency films, (most especially Provia),
>that there is a considerable difference in color balance from roll to sheet
>films.  It would be interesting to see if this difference carries over to
>resolution differences.  Another thing you might consider trying would  be to
>use a microscope (if one is available to you) for your final comparison.
>
>By the way, I do understand what you are trying to accomplish with your 1
>sq. cm piece of film, and I applaud your sticking to your guns over this
>issue.  Good luck with future experiments.
>
>Karl Wolz
>
>

I agree with Karl's comments. If you are trying to see what the system resolution is like direct measurement of it is about the only way. Kodak publishes MTF curves for most of its films. The conditions and method used for measurment can be requested from Kodak. This data indicates there is _no_ difference in resolution between films of different formats coated with the same emulsion. And, high resolution emulsions are available in all formats. Resolution is just as you define it. It has nothing to do with the size of the film.

Obviously, a larger piece of film can record more data than a smaller piece but the data _density_ is a characteristic of the emulsion. That's why its measured in line pairs per. millimeter.

Another factor which complicates resolution measurement is that it varies with image contrast. This shows up in the shape of the MTF curve. The lower resloution for low contrast targets is partly the result of scattering and irradiation in the emulsion and halation from the support. These have been minimised in modern films.

I say that system resolution must be measured directly for several reasons. First, the shape of the MTF cures of film and lenses is different. For that reason there is no simple way of calculating the combined resolution. One often sees the formulas 1/t= 1/f + 1/L where t= total resolution, f= film resolution, and L= lens resolution, or the square root of the sum of the squares of the two resolutions but both of these are only very rough approximations. The error becomes larger when some other element is introduced such as an enlarging lens and paper resolution.

In addition, and maybe more important, it is vey difficult with real world equipment to determine the effect of film plane flatness and accuracy other than direct measurement.

So it would seem your definitions are OK and you seem to understand just what it is you are measuring.:-)

---
Richard Knoppow
Los Angeles, Ca.
[email protected]

From: "Christopher M. Perez" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: System testing madness - Continued
Date: Mon, 03 Aug 1998

NYCFoto wrote:

> >>>- TMax100 and several color films have a resolution limit of around  100 to
> 120lines/mm at 1:6 contrast ratio<<<
>
>         According to the kodak dataguide book, the resolution for Tmax 100 is 200 (
> i'm not certain if this is lines/mm) 320 for techpan, 100 for tri-x and 120 for
> t-max 400.

It might be worth checking the contrast ratio for the numbers quoted in the Kodak reference. In the "real world", that is to say using tests people have done and reported elsewhere on the web and in print media, using 1:6 contrast ratio to describe typical scenes in nature and the studio the finest grain films resolve around 100 to 120 lines/mm. All films report better resolution than these numbers, but they are invariably recorded at much higher contrast ratios (ie: at ratios most photographers never shoot at!).

> I shoot LF far more than I shoot MF and my opinion is as follows.   I think
> that at a given degree of magification a lens designed for 35mm or MF ( and I'm
> talking top quality lenses for these formats, not amatuer stuff) will be
> optically  superior to LF lenses for a simple reason.  LF lenses are  designed
> to have greater film coverage since they need to take into account coverage for
> camera movements.

This was the foundation understanding I started with too. HOWEVER, my thoughts are changing rapidly given the tests Kerry Thalmann and I have been performing over in r.p.e.large-format. The original assumption is beginning to cumble. It began when I first noted the very fine performance of a Kodak 135mm Wide Field Ektar that covers 80 degress. Many other large format lenses are also performing at or better than this lens' capabilities. It's no longer a surprise to me to know that certain LF optics will easily resolve 80 lines/mm _on film_...

But I'm not ready to close the book, as it were, on MF having superior optics to LF. Hence my request for support in the testing effort. If the Mamiya lens I tested is not truely representative of what MF lenses currently resolve, I'd like to learn it soon... and before I shoot my mouth off and embarass the h**l out of myself by saying something stupid. :-)

I hope this helps clarify.

- Chris

Date: Mon, 10 Aug 1998
From: "Dr. Ulrik Neupert" [email protected]
To: [email protected]
Subject: Re: Traffic

> In the Hasselblad Forum, Issue 1 1997, volume 33, page 37 this is
> discussed.  For the benefit of those who do not subscribe:
>
> Q.:  "Newer magazines have a friction brake.  What is this for? I have been
> told that these magazines can even give sharper pictures?"
>
> A.:  "The hub of the film spool in the spool holder was originally designed
> to offer the least possible resistance to the rotation of the spool.  And
> we thought that this was the correct way to do it.  But as a result of the
> continuous reviews and product improvements we carry out, someone realized
> that the film was not always held tight and flat over the image frame.  The
> film was "loose" and this could also affect the spacing between  frames.  We
> found that by braking the hub on the exit side we could tension the film
> and improve flatness and frame division.  The friction brake was developed
> and introduced.  It is easy to check whether a magazine has a friction
> brake or not.  The braked hub has two wings.  A hub without brake is
> entirely concentric.  Because a magazine with a friction brake has
> considerably better performance we recommend you to trade it in!"
> -----------

A Hasselblad technican here in Germany told me one year ago that they do not built the friction brake into the magazines any more (too much friction). He told me that there is no difference in picture quality (film flatness) when compairing the 12 and A12 models and subtypes. Thats just what he told me, no personal scientific experience.

Ulrik

From: [email protected] (Richard J. Fateman)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Rolleiflex film flatness - questions/comments
Date: 8 Oct 1998

Christopher M. Perez [email protected] wrote:

>I come seeking advice.  I just tested an early Rolleiflex MX with Schnieder Xenar 75mm
>f/3.5 taking lens (see http://www.hevanet.com/cperez/MF_testing.html for the actual
>results if needed).
>
>- I note that the frame edges are v.sharp (40 to 70 lines/mm depending on f-stop)
>
>- The center is v. _un-sharp_ (22 to 50 lines/mm depending on f-stop)
>
>Question: is there a film flatness problem with these cameras?

Not especially. In fact the flatness is probably better than SLRs like Hasselblad, with tight bends in the film path. I suppose there is a possibility you are not winding the film tightly on the reel. It sounds to me like your camera was not focused right. The focus should be optimized so you get max sharpness at the center. So perhaps the viewing and focus lenses are not aligned. Or perhaps you have the film pressure plate in the wrong position (if there are 2 settings).

Your Xenar (= Tessar) lens should be quite sharp in the center but perhaps softer on the edges until you stop down some. The Schneider Xenotar = Zeiss Planar formulation is supposed to be sharper across the width of the negative when wide open, but is alleged to be not as contrasty as the Tessar. I don't know what the Mamiya TLR 80mm lens is.

Old lenses may also suffer from various problems like fungus..

>Question: are the newer Rollei's film flatness better controlled?

The newer TLRs are about the same so I would not expect that to change.

--
Richard J. Fateman
[email protected] http://http.cs.berkeley.edu/~fateman/

From: Kerry Thalmann [email protected]
Newsgroups: rec.photo.technique.nature
Subject: Re: Loss of sharpness from f-16
Date: 9 Oct 1998

David Hay Jones wrote:

>    I wonder whether loss of sharpness at f16 to f32 etc is one of those
> test lab problems, where you see the difference on charts based on lens
> tests in a lab but you don't see the difference at the size most pics
> are enlarged or published.

Hi David,

This loss of sharpness is very real and can be easily observed both in test shots and "the real thing". Diffraction is a physical principal whose effects are well understood and easy to predict. It doesn't matter if you buy the most expensive, highest quality lenses on the planet, they will still suffer from diffraction at small stops. Whether or not this loss of shaprness is significant depends on the degree of enlargment in the final print, and your personal definition of acceptable sharpness.

Where diffraction starts to limit the sharpness is also a matter of format. F22 is a commonly used aperture in 4x5 (most large format lenses stop down to at least f45, f64 is common and I even have one modern LF lens that stops down to f128), and most modern large format lenses are optimized for best overall performance at f22 (or f16). Many are sharper at the center of the field at wider stops (f8 and f11), but are soft in the corners until you stop down to f16 or f22. By the time you get down to f32, most large format lenses begin to show the effects of diffraction. And yes, I can see the loss of sharpness when shooting real subjects (not just test charts). I examine all my transparencies with a high quality 8x loupe. I hardly ever shoot at f45 anymore, because the difference in sharpness between f22 and f45 is significant (to me). I do still use f32 when I need the depth of field for complex three dimensional subjects. Although there is some overall loss of sharpness, it isn't too bad (IMHO).

All this has been confirmed by the large format lens testing Chris Perez and I performed this past summer. We tested approximately 65 large format lenses of various ages, brands and focal lengths. Almost all of the lenses we tested performed their best overall at f16 or f22. Only a couple were best at f32. After a while, we stopped testing at f32, since most lenses performed similarly when stopping down that far (the exception was slower lenses or longer lenses that would likely be used at f32).

The results of our lens testing can be found at:

http://www.hevanet.com/cperez/testing.html

Again, whether or not this loss of sharpness is significant depends on the degree of final enlargement. If you shoot 8x10 and contact print, you can get by with some pretty horrid (in terms of resolution) lenses and you can stop down to f45 or f64 and still get acceptable results. On the other hand, if you shoot 35mm and plan to make 16x20 (or larger) enlargements, you'll want your original negative as sharp as possible. Chris and I have not done any tests on 35mm lenses, but from what I've read on the subject, most modern 35mm lenses are at their sharpest in the f5.6 - f 8 range.

>    Also, there's a balancing act between depth of field and this alleged
> loss of sharpness. Sometimes we need to stop down to f16 and smaller for
> greater
> depth of field and I can't in my experience say that the loss of
> sharpness is a great problem. But sure the problem is there, the test lab
> people have proved that.

Yep, it is often a trade-off of a small loss of overall sharpness vs. greater depth of field (that's why camera movements are so handy in large format - but even with the movements, stopping down is often necessary for complex subjects). It's nice to understand how your lenses perform at different apertures, so when the time comes you can make an informed decision. There has been a lot of research and tesing of modern 35mm lenses, but it is not something I follow closely. Does anyone know of a web site with some actual on-film test results for some modern 35mm lenses? Or better yet, has anyone done their own tests? BTW, I highly recommend anybody serious about lens sharpness try testing their own lenses at least once. All you need is a test chart and a roll or two of film. You can shoot the tests indoors at night or when the weather is bad outside. And from one evening's effort and minimal expense, you can learn how each of your lenses perform at all apertures. Some will point out that the results are only valid for two dimensional, high contrast test targets. This is true for the exact numbers (in line pairs per millimeter), but what is really important is not the actual numbers (unless you are trying to win a "my lens is better than your lens" contest), but the relative numbers. It will let you know which apertures give the sharpest results for each lens and how your lenses compare to one another. I think this information is worth the small investment of time and money (if nothing else, it gives you something to discuss in rec.photo.* when times are slow).

Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://www.thalmann.com/

From: [email protected] (Zane)
Newsgroups: rec.photo.technique.nature
Subject: Re: Loss of sharpness above f-16
Date: Fri, 09 Oct 1998

Larry Brusso wrote:

>Hi gang,
> I've noticed several people comment on seeing a loss of sharpness when
>stopping down below f-16. Can anyone expand on this a bit?
>Is this phenomenon more prevalent in zooms than primes?
>How about focal length?
>If there is a significant loss of sharpness at the smaller apertures,
>than why stop down below f-16? What good is additional depth of field at
>the cost of image sharpness?
>Opinions......
>How bout' Rick, wana jump in here?
>
>Larry (a victim of phonics)

Larry

Diffraction limits the resolution of a lens to about 1600 line pairs per millimeter divided by the f/no. For example, at f/16 a perfect lens would give 100 lp/mm, at f/32 50 lp/mm, etc. Since the lens and film capabilities already limit the resolution, the diffraction gets added (sort of) to it and starts to make a difference at about f/16. Personally, I don't start to take any account of it for most lens and film combinations until f/22.

This is a fact of life for any lens. Of course, the sharper the image without diffraction, the more difference it makes. That would be the only consideration of zooms vs primes--i.e. the zooms might be limited to only about 50 lp/mm on film anyway (depending on the zoom).

Cheers
Zane

From: "Christopher M. Perez" [email protected]
Newsgroups: rec.photo.equipment.large-format
Subject: More 'system' testing
Date: Thu, 15 Oct 1998

As everyone is by now most painfully aware, Kerry Thalmann, Mike McDonald, and I have been testing various lenses in various systems. We're getting down to the end of it.

I've come to learn that glass is just glass and the way it gets poured, ground, aligned, cemented, and installed in systems is pretty much the same across all camera/system types. To me, this would mean that all systems should resolve very similarly. Where a lens designer can take advantage of narrow angles of view, such lenses might resolve better than lenses required to cover very wide angles of view. But this might be a minor consideration given all the other factors that go into making any system 'sharp'. _To me_, a minimum of 60 lines/mm to film would indicate that a system is 'good' Anything better than this is wonderful. But until now I didn't really have 'proof' of this.

Check out: http://www.hevanet.com/cperez/MF_testing.html and compare the latest results against the LF lenses previously posted. Pay particular attention to the Mamiya 6 MF, Fuji GW690III, Bronica SQA, and Mamiya C220Pro medium format systems. Then consider results from the typical modern LF lenses from Schneider, Rodenstock, and Fuji (110XL, 120 Super Symmar HM, 150 Sironar-S, and Fuji 240 A - as examples).

At similar cost of ownership it appears that MF and LF systems return similar resolution to film. The 'exception' being the Mamiya 6 MF. It returns approximately 15% better resolution than the best LF lenses we tested. I have also received private email that indicates Rolleiflex 2.8 Planars can return just over 100 lines/mm to film. Good resolution improvement over the best LF lenses, but _not_ what I'd consider overwhelmingly outstanding. And, we've not yet had a chance to test the best narrow angle LF lenses (APO Ronar, or Repro Claron).

I've previously stuck my neck out and claimed that the difference between good LF and MF lenses/systems is minimal at best. I know I've 'tee'd' off more than a few people by saying this. My intent is not to anger, rather to learn _for myself_ and to _educate myself_ on the differences between various lenses, manufactures and systems. Secondarily, I hope in sharing this information more than just myself become more deeply versed in our chosen field of endevour. Everyone is, of course, free to draw their own conclusions.

I hope this proves useful to those interested in such things...

- Chris

From: "Christopher M. Perez" [email protected]
Newsgroups: rec.photo.equipment.large-format,rec.photo.equipment.medium-format
Subject: Concerning Price vs Performance - a modest proposal
Date: Thu, 15 Oct 1998

I have been trying to come up with a way that I can evaluate lens and system costs vs. performance. I think I've hit upon one useful mechanism. Hence this Modest Proposal for evaluating the relative costs of performance for Large Format lenses and Medium Format systems.

I believe _one_ way to evaluate performance vs cost can be described by:

{cost of item} / {max. resolution of item to film } = {cost of one line 
per mm
of
resolution}



Here are several examples of what falls out of this calculation:


90mm Angulon - $200(used) / 67 l/mm       = $2.98 / line / mm

3 1/2" WARaptar - $125(used) / 60 l/mm    = $2.08 / line / mm

90mm SW Nikkor - $750(used) / 80 l/mm     = $9.30 / line / mm

90mm SW Nikkor - $1350(new) / 80 l/mm     = $16.80 / line / mm 

110mm Schneider XL - $2300(new) / 80 l/mm = $28.75 / line / mm

135mm WF Ektar - $375(used) / 76 l/mm     = $4.90  / line / mm

150 mm APO Sironar S - $750(new) / 85 l/mm = $8.80 / line / mm

150mm Symmar Convertable - $300(used) / 64 l/mm = $4.60 / line / mm

200mm M-Nikkor - $450(used) / 67 l/mm     = $6.70 / line / mm

203mm Kodak Ektar - $200(used) / 67 l/mm  = $2.98 / line / mm

210 APO Symmar - $750(used) / 76 l/mm     = $9.80 / line / mm

210 APO Symmar - $1000(new) / 76 l/mm     = $13.10 / line / mm

Bronica SQA w/ 80mm - $800(used) / 67 l/mm        = $11.90 / line / mm

Fuji GW690III w/ 90mm - $1000(used) / 67 l/mm     = $1492 / line / mm

Fuji GW690III w/90mm - $1300(new) / 67 l/mm       = $19.40 / line / mm

Kodak 620 Special w/100mm = $15(used) / 63 l/mm   = $0.23 / line / mm

Mamiya C220Pro w/80mm - $225(used) / 67 l/mm      = $3.35 / line / mm

Mamiya 6 MF w/80mm - $2800(new) / 95 l/mm         = $29.47 / line / mm

Mamiya 6 MF w/80mm - $1800(used) / 95 l/mm        = $18.95 / line / mm

A couple things fall from this. 

- It could be argued _based purely on these numbers_ that the best value per line of resolution in LF is an old 3 1/2" WA Raptar or the 203mm Ektar. They'll both cost a person less than $3.00 per line per mm of resolution.

- In MF the winner, hands down, is an old Kodak Special Six20 with 100mm f/4.5 Kodak Anastigmat. It wins by costing only $0.23 per line of mm of resolution!!! More reasonably the Mamiya C220 Pro comes out costing a person only $3.35 per line of resolution.

So my modest proposal is: When newbies ask what the best value for their money is, simply take it's cost, divide it by the number of lines per mm of resolution it's capable of returning, and evaluate competing systems based on the lowest cost per line of mm of resolution...

I hope this spins a few thought wheels... :-)

- Chris

From: Christopher Perez [email protected]
Newsgroups: rec.photo.equipment.large-format,rec.photo.equipment.medium-format
Subject: Modest Proposal - part II
Date: Fri, 16 Oct 1998

Bob Wheeler implied that there should be some minimal requirements for enlargements being made from LF and MF equipment (at least this is what I think he was implying). We can calculate these requirements as follows:

{line/mm eye resolves} x {neg/trans enlargement factor} = {minimum l/mm required to fully resolve what the eye can perceive on final print}

This will give a good starting reference for establishing the minimal system resolution requirements. In directly, one can use this to determine if their photo system is capable of delivering the desired resolution.

If we assume full frame enlargements (no cropping), a tripod is used in all cases (to eliminate shake from the system), a 'good' enlarging system (no loss of resolution from neg/trans to print), and the fact 'young' human eyes are reported to be able to resolve 7 lines/mm, the following can be assumed:

For 4x5 negatives and transparencies:
- 8x10 inch prints require a system to resolve 14 lines/mm
- 16x20 inch prints require a system to resolve 28 lines/mm

For 6x6 negatives and transparencies:
- 8x10 inch prints require a system to resolve 28 lines/mm
- 16x20 inch prints require a system to resolve 61 lines/mm

For 6x7 negatives and transparencies:
- 8x10 inch prints require a system to resolve 25 lines/mm 
- 16x20 inch prints require a system to resolve 51 lines/mm

1. To make a 16x20 print from 6x6 requires all the resolution that many of the MF systems Mike, Kerry, and I tested can deliver.

2. It would take a really poor LF lens to resolve the 28 l/mm required to enlarge from 4x5

3. If one works in 6x7 the requirements are less stringent than 6x6 to reach 16x20, but a system must still be 'pretty good'.

4. When reviewing our tests on folding cameras (specifically the Balda and Kodak Special Six20) one can see there is adequate resolution for most tasks. _For me_ this means portability of photo equipment when working in field need not become a consideration as long as I don't mind using just one lens (ala Henry Cartier-Bresson :-).

5. Almost any camera can resolve the numbers required to print a great looking 8x10... :-)

I hope this helps...

- Chris

From: "Bob Salomon" [email protected]
Newsgroups: rec.photo.equipment.large-format
Subject: Re: More 'system' testing
Date: Sat, 17 Oct 1998

Obviously I am with Rodenstock. Just check my signiture below.

But that has nothing to do with my comments regarding these tests.

They are inconclusive and misleading.

For example:

They tested 6 90mm 6.8 Angulons and then posted publicly a cost per mm based on one of them. But if you look at the test results they posted test results on 3 of them at 11, 16 and 22 and 3 at 16, 22 and 32.

At 22 the best tested at 61, 68 and 61 lpm and the worst at 30, 30, 21 lpm.

Now they post a cost per mm with from this test with no indication that they had to test 6 lenses to find the one they mentioned in their public post. You might assume from that post that all 90mm 6.8 Angulons had the performance/cost ratio they posted.

Boy would you have been fooled.

HP Marketing Corp. U.S. distributor for Amazon, Braun, Gepe, Giottos, GO Light, Heliopan, HP Combi Plan T, Kaiser fototechnik, KoPho cases, Linhof, Pro Release, Rimowa, Rodenstock,Sirostar 2000

From: [email protected] (John Hicks)
Newsgroups: rec.photo.equipment.large-format
Subject: Re: More 'system' testing
Date: 17 Oct 1998

I believe what Bob S. is getting at is that the quality of old lenses was rather variable; it was common practice to take several for testing and pick the one that was best. With modern lenses there's very little need for that.

Also please note that he's one of the very few reps who bother to participate in the newsgroups. Others have dropped in but quickly decided that it wasn't worth the hassle.

---
John Hicks
John's Camera Shop

From: gene [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Why are MF lenses poor
Date: Thu, 22 Oct 1998

I'm curious as to why MF lenses cannot be made to have resolution comparable to 35mm lenses. I shoot professionally with pentax 645 equipment, Mamiya RB67's, and Canon EOS with a bunch of L-series zooms, and although the medium format looks better at 16x20 or better. The 35mm stuff tends to be just as sharp at 16x20 if not better than the MF stuff.

I just cannot understand why fixed focus lenses for MF cannot be as sharp or sharper than 35mm zooms. Does it have something to do with the additional coverage necessary to cover the larger neg? I remember a couple of years ago reading a test in popular photography when they tested a 50 f1.4 planar on a 35mm camera and got 110 lines/mm, and when they tested an 80 f2.8 planar on a hasselblad they only got about half the resolution.

It seems that 35mm lenses are improving all the time while hasselblad has been using many of the same designs that they were using 30 years ago. I'm using the latest optics on all my equipment, but I'm frustrated with MF lens quality.

From: [email protected] (Zane)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Why are MF lenses poor
Date: Fri, 23 Oct 1998

> I'm curious as to why MF lenses cannot be made to have resolution  comparable
>to 35mm lenses.

(snip)

Gene

Most of the main optics aberrations come out expressed in angle as a function of f/no and field angle without reference to the size of the lens elements. Suppose you design a nice 50 mm lens and it gets 100 lp/mm at some field angle, limited by astigmatism. This is an angular aberration of about 0.2 milliradians. To get the same coverage with MF, you need roughly twice the focal length (100 mm), so let's say you use the same design and just scale everything up by a factor of two in size. That 0.2 milliradians now limits the new 100 mm lens to 50 lp/mm.

For a 100 mm lens made for 35 mm format, you can get less angular aberration because a 100 mm lens only has to work 1/2 the field angle of a 50 mm lens and the 100 mm MF lens. The designer doesn't have to sacrifice resolution at the smaller field angles to get acceptable performance at the larger angles.

You can compensate some for the above facts of life by adding more lens elements to the 100 mm MF lens (more than a 50 mm lens for 35 mm format). But at some point cost and the build up of manufacturing tolerances will get to you.

Cheers
Zane

From: "D. Cameron" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Why are MF lenses poor
Date: Fri, 23 Oct 1998

> Gary Helfrich wrote:
> > Sharpness is important to a point, but should not turn into a fetish.    

Well said, indeed. I never really worry about lens performance. I buy good stuff and USE it. By the way, if you aren't using a tripod or camera stand and cable release, the difference between a lens which resolves 50 l/mm and a lens which resolves 100 l/mm is a moot point. Neither lens will perform up to potential without a steady support. Way back when, I used to work in a retail camera shop and it always amazed me how amateurs would spend big bucks on a camera (looking for the best glass, don'tcha know) and then try and get away with the most spindley cheapo tripod on the rack.

From: [email protected] (BHilton665)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Quality 35 mm lenses vs. medium format
Date: 23 Oct 1998

> From: Greg Kerr [email protected]
>
>(2) At what size of a print does one really notice the difference
>between 35 mm and medium format.

I shoot both formats (Canon EOS w/ L lenses and Pentax 645) and usually shoot Velvia or T-Max 100 film, always from a tripod when shooting a scene I may want to blow up. I also try to shoot at f/8 or f/11 whenever depth of field constraints allow it. In other words, fine-grained film under conditions that should let me make the best possible large prints.

For my tastes the 35 mm prints look great up to about 11 x 14 " and then start to tail off. Ok at 16 x 20 but not really great ... the 6 x 4.5 film prints look great (to me) all the way out to 20 x 24. Haven't printed anything larger but I'd guess if you want prints much larger than this it's best to start looking at 6 x 7?

Others may place these cross-over points at different print sizes, but as a generalization it's obvious to me that the bigger film definitely produces better large prints. That's the ONLY reason I'm shooting medium format :)

From: Peter Olsson [email protected]
Subject: Response to A comparison of 35mm and MF optical quality
Date: 1998-10-26

Interesting Marco, I have made similar testings myself, comparing Nikkor-lenses to Hasselblad lenses. Medium format was the clear, undisputed winner every time, both in b&w and in color (I have to admit though that during one of the tests my 1= year old nephew put his head in a bucket, standing right behind my "test-setup" and I ripped for the Auto-focus Nikon to capture that moment!).

One comment, I think I would have down-loaded more of your test- images if they were smaller. Perhaps you could show only some details and get smaller files?

Date: Sun, 15 Nov 1998
From: Eric Goldstein [email protected]
To: [email protected]
Subject: Re: [Rollei] Coatings: T* vs HFT

Dr. James Chow wrote:

> I don't see why coatings would affect sharpness other than a
> reduction in contrast from flare.

Dr. Jim-

Different coatings may effect *perceived* sharpness. From my readings on this subject, I've come across the fact that all things being equal, higher contrast images are perceived as being "sharper" than flatter less-contrasty images, though they may in fact have lower resolution. This, along with the fact that relatively few negatives are enlarged beyond 8 diameters, is why lens manufacturers in the '70s began biasing or apotizing their lenses in favour of contrast over resolution.

Eric Goldstein

Date: Tue, 24 Nov 1998
From: Jim Bielecki [email protected]
To: [email protected]
Subject: [Rollei] Re: Film Flatness

>The real solution to this problem should be out soon in the Contax 645, for
>which there will be a vacuum back for 220 built just like the vacuum back
>on the 35 mm Contax RTS III.

Don't forget that the Rollei 70mm back offers the vacuum option too.

Date: Tue, 24 Nov 1998
From: Tim Ellestad [email protected]
To: [email protected]
Subject: Re: [Rollei] Re: Film Flatness

120 (especially) and 220 film is notorious for not exactly laying flat. I don't think that focus or sharpness is the issue in that these focal lengths on this size negative yield a pretty forgiving depth-of-focus. It's image geometry that gets a little gorked out. Architectural photographers notice this, particularly near the sides of the frame.

In 120 the paper backing doesn't earn any high marks here. The light weight film base in 120 and 220 fosters the problem and the tightness of fit between the rails and the pressure plate is usually comfortably roomy (check the flange/focal depth sometime without as well as with various films) to accommodate the heaviest films (TMAX100 for instance).

Mannheim talks about this in his book on the SL66. He describes a test you can do by advancing a frame, quick pulling the magazine and dark slide and watching the mirror reflection of something like venetian blinds on the emulsion surface. In about 30 seconds the film will likely "relax", giving up it's flatness. Cameras with contorted film paths like SL66's, Hassy's, etc. have the greatest trouble with this, but a friend of mine who is an architectural specialist has had a fair amount of this trouble with rollfilm magazines that he uses with his 4x5 Sinar.

Tim Ellestad

Date: Tue, 24 Nov 1998
From: Richard Lahrson [email protected]
To: [email protected]
Subject: Re: [Rollei] Re: Film Flatness

...

For roll backs (I"ve got a Graflex roll back that doubles back like the Hasselblad, Mamiya 67, Mamiya 645 and Bronicas) you can feel the bulge in a darkroom. It seems to "take the bulge" at the point where the film bends 180 degrees. So, if left unused for awhile in the camera, the film will bulge on the exposure after the one that's ready to fire.

Rich Lahrson
[email protected]

Date: Wed, 25 Nov 1998
From: Ferdi Stutterheim [email protected]
To: [email protected]
Subject: Re: [Rollei] Re: Film Flatness

Hello all,

I have limited experience with the "plane glass". The only thing I did was taking it out and storing it in a very secure place. They are rare and break easily. Well, I used it a few times. The main problem is they become dirty and this dirt will appear perfectly sharp on the film. Not just avoidable general dirt, but also emulsion deposits.

Ferdi Stutterheim

Date: Wed, 25 Nov 1998
From: Bob Shell [email protected]
To: [email protected]
Subject: Re: [Rollei] Re: Film Flatness

>Is this vacuum back a solution in search of a problem.  I've not heard  of too
>many complaints of film flatness distortion prior to this "fix".

There is a detailed technical paper by Dr. Sygaya showing how film, even 35 mm, is not held really flat in cameras. The degree of bowing or curving varies with camera design and film type, but it is real. Apparently, Zeiss thought that such a system in the Contax RTS III was the only way to take full advantage of some of their lenses. Lack of film flatness is much more of a problem in medium format than in 35 mm, so it could be more important, particularly for high tech applications.

Bob

Date: Mon, 23 Nov 1998
From: Bob Shell [email protected]
To: [email protected]
Subject: Re: [Rollei] film flatness

...

Several years ago I did some tests of film flatness in MF cameras. As expected, the smaller the frame size the flatter the film, with 645 cameras generally holding the film much flatter than 6 X 7 cameras. I could not test TLRs or fixed lens cameras like the Fuji without dismantling the cameras, and didn't test them.

Cameras which use a reverse curl, like the Hasselblad, do put a kink in the film, so pausing in mid roll for more than a few hours is not recommended since the next frame after a long pause is likely to have a nice kink in it. This is not a problem with cameras like the Rollei TLRs and 6000 series, since they feed the film straight.

The real solution to this problem should be out soon in the Contax 645, for which there will be a vacuum back for 220 built just like the vacuum back on the 35 mm Contax RTS III.

Bob

From: Kerry Thalmann [email protected]
Newsgroups: rec.photo.equipment.large-format
Subject: Re: READYLOAD and Sharpness
Date: 21 Nov 1998

mwestling wrote:

> What a load of crap!
>
> Numerous magazines have done film flatness tests and shown that the
> Readyloader holder is the best for film flatness, second only to the
> ridiculously priced ($400) Sinar vacuum back...

Could you please cite references for such magazine articles? I've seen two such articles (View Camera, March/April 1996, "A Battle of the Bulge: Sheet Film Holders" by Cervin Robinson and Camera & Darkroom April 1995, "Readyload, Quickload, Shoot - A Comparison of 4x5 Film Holders" by Joe Englander). Neither article supports your assertion above.

In the article by Robinson, he concluded that the Kodask Readyload holder performed very well (WRT film flatness), but the old, wooden Graphic Holders (conventional double sided holder that is the predecessor to today's modern plastic film holders) and the Grafmatic also performed quite well (with best overall performance going to the wooden Graphic holders and the Koad Readyloads).

However, in the Camera & Darkroom article, Englander comes to a very different conlusion. His test was much more scientific and thorough than the previously mentioned article. Without going into all the details, his test set-up was much more controlled, he presented both accurate measurements of film position (center, plus all four corners) and complete photographic data to support his conclusions. Robinson's conclusions were much more subjective, and he only considered center performance, not corner performance (as such, he wasn't really testing "film flatness", merely the location of the center of the film in the holder WRT the location of his camera's ground glass).

Englander tested the Fuji Quickload, Kodak Readyload, Polaroid 545i, Grafmatic and conventional Riteway holders. The ideal location of the film surface in these holders is 0.190" (ANSI standard of 0.197" minus the thickness of the film 0.007"). Without re-typing his whole article, I'll just provide data for the Readyload (the worst) and the Grafmatic (the best). For the Readload, the position of the film in the holder ranged from 0.214" (top two corners) to 0.190" (bottom right corner) and the center was at 0.204". The Grafmatic ranged from 0.187" (top left corner) to 0.192" (top right and bottom left) and the center was at 0.189". As you can see, the Grafmatic was not only much more accurate, but also much more consistant across the entire sheet of film. Of the other holders, the Riteways were next best, followed by the Quickload and the Polaroid. The photographic test results he presented correlated 100% with the measured data. The Readyload results were indeed the least sharp (especially at the corners) and the Grafmatic was clearly the sharpest overall (although the Polaroid was quite sharp at the corners, but notciably softer in the center).

Keep in mind that these results are based on a limited sample size (but they certainly don't support Mark's assertion above). I am inclined to belive that the tolerances involved in manufacturing something like an inexpensive, plastic film holder (Like the Koad Readyload at $50) are such that results (and conclusions) may vary from sample to sample. Such holders are also subject to environmental variances and mechanical stresses when used in the field (expansion, contraction, humidity, warpage, etc.). Also, wether or not such differences will show up in the final results depends on MANY other factors (accuracy of focusing, location of ground glass relative to film plane, lens performance and f-stop, film resolution, enlargement ratio, enlarger lens performance, enlarger vibration, film flatness during enlargement, subject matter, viewer's eyesight, etc. ...).

> I suggest you check you techniques again...
>
> Mark    

Still, given the two articles I have read on the subject, I would tend to not discount Les' experience below nor blame his technique (I certainly wouldn't call it a "load of crap" without presenting supporting data or citing references). Afterall, he got good results with conventional holders (unlikely if his technique was flawed) Perhaps Les just got a bad Readyload holder and Mark got a good one. Perhaps the location of Les' groundglass is better matched to his conventional holders and Mark's is better matched to his Readyload holder. In any case, it is always best to test your own SYSTEM and determine if the results are satisfactory for your needs.

Kerry

> Les Baldwin wrote
> >"Bill K." wrote:
> >                                
> >
> >> Has anyone had a problem with sharpness at one end of the 4x5 film ?
> >
> >YES, I did. When I first started in LF just over a year ago, I was using
> >Kodak Readyloads. I was trying despertly to take a shot of the mansion
> >where my wife and I got married. I went to the location four seperate
> >times with a new readdyload holder and fresh films from Kodak. I was
> >using E100S to learn on. For the first 10 images I shot from the box, I
> >had a small area along the bottom of the frame out of focus ever so
> >slightly. However since I had only had my Horseman for two or three
> >weeks I thought It was me. The camera had been bought used but checked
> >out by our in house tech and given a clean bill of health.
> >So I asked many of the local pros and come to find one that had similiar
> >problem about five years ago. He suggested that I take a few pieces of
> >film from the readyload packets and put them into one of my regular film
> >holders. Voila!!!! razor sharp trannies. Just in time  I had some good
> >shots printed up matted and framed in time for our anniversary. So now I
> >take the "new" readyload holder back where I got it and exchanged for 
> >another in a sealed box. New holder, new film same prob. I will never
> >use readyloads again. I know that some shooters use the 545I POL back
> >and some use the FUJI, but I refuse. It was then brought to my
> >attention, the story about different film holders in VC magazine. They
> >also quoted the probs with readyloads and light leakage and film plane
> >flatness....
> >Hope this helps.
> >
> >
> >take care
> >
> >Les
> >
> >http://www.fotosfx.com 

Date: Wed, 25 Nov 1998
From: [email protected]
To: [email protected]
Subject: Re: [Rollei] Re: Film Flatness

In a message dated 98-11-25 00:08:28 EST, you write:

120 (especially) and 220 film is notorious for not exactly laying flat. I don't think that focus or sharpness is the issue in that these focal lengths on this size negative yield a pretty forgiving depth-of-focus. It's image geometry that gets a little gorked out. Architectural photographers notice this, particularly near the sides of the frame. Look, I don't doubt certain film travel paths may introduce some bend and even grant this may result in unwanted results when involved in technical or scientific work. But let's face it, when talking about using these cameras for the 99.9% of the situations they are ACTULLY employed, no problems are encountered. Its great there are companies that can address a "problem" encountered by the few photographers needing the fix. Don't get too carried away with the solution. Keep in mind the constant reference to "bent" film in the other responses. In actuality, the variance introduced is barely appreciable.

From: [email protected] (Zane)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: mtf to lpmm conversion
Date: Wed, 25 Nov 1998

William Robinson [email protected] wrote:

>I find it interesting that most photographers refer to lines per
>millimeter ratings for lenses, while manufacturers always talk about mtf
>graphs. Is there any way to covert one to the other, either by formula
>or subjective approximation? I (as a photographer) am especially
>interested in the mtf to lpmm direction.

Hi William

The MTF is the contrast plotted against either spatial or angular frequency. When it's spatial frequency, the units are usually 1/mm, or lines per millimeter, or line pairs per millimeter (usually the same thing). Most often, this is the contrast that one would see imaging a series of perfectly black and white bars. For example, when the bars are at a frequency of 30 pairs per mm on the film, a particular lens might show them with a contrast of 60%. This would be one point on the MTF curve. At 60 pairs per mm, the MTF (contrast) value might be down to 20%.

When people talk about just the lp/mm capability of a lens, they're usually referring to the value at which the contrast (or MTF) effectively goes to zero. Having MTF values at other spatial frequencies and at different positions in the lens field of view is, of course, the best. For example again, one lens might have a maximum lp/mm capability (where the contrast goes to zero) higher than another, but the second lens might have higher contrast at lower frequencies. (This is a common situation.) The second lens might then give much more pleasing results. This is why people use MTF graphs for best determination of a lens' performance.

Zane

ec.photo.equipment.medium-format
From: [email protected]
[1] Re: 35mm vs. medium format :Questions for the pros
Date: Thu Dec 03 04:53:15 CST 1998

I use both 35mm and 6X4,5. In 35mm I only prime lenses; some of the among the best ever made. I use them at their best aperture and always use a 6kg Gitzo 500-series tripod. I also use mirror lock. The difference between 35mm and medium Format is HUGE. It has nothing to do with print size. The differences are stunning in side by side comparisons with the Velvia slides on the light table. It may very well be that some people thinks that 35mm is good enough. It's hard to argue such an opinion for an opinion is all it is. Who knows whats good enough. However, the differences are significant. Whether you care for that quality gain or not, is a purely personal matter.

Paal

rec.photo.equipment.medium-format
From: [email protected] (BHilton665)
[1] Re: 35mm vs. medium format :Questions for the pros
Date: Thu Dec 03 13:05:01 CST 1998

I also use both formats with top quality lenses and shoot mostly Velvia and T-Max 100. I agree totally with Paal's statements. Personally the 35 mm enlarges fine up to about 11 x 14 Ilfochromes (for my tastes anyway) and is somewhat marginal (again for my tastes) at 16 x 20 or higher. I use 35 mm for many situtations but if I can put it on a tripod I'll always choose MF ... just another opinion ... in the final analysis it depends on either what YOU want if you're amateur, or what your CUSTOMERS want if you're shooting pro anyway.

rec.photo.equipment.medium-format
From: [email protected]
[1] Re: 35mm vs. medium format :Questions for the pros
Date: Thu Dec 03 05:13:27 CST 1998

[email protected] wrote:

Jeffrey,
Tht is an interesting post. I would argue similarly, but with quite a few caveats:

1. with perfect negatives/slides of a very slow/high res emulsion, enlarged to the same dimensions, it will take VERY large prints to get a quality advantage noticeable enough to evidently justify the investment in MF. But a "marginal" quality advantage in favour of MF is noticeable for the keen observer even at more moderate dimensions (I can generally trace it from 13x18 cm up). Some people value that "marginal" advantage very highly. Velvia Ilfochromes are a real visual boost to 35mm quality though: on blind tests, fellow photographers were positive the 20x30 cm prints I showed them came from MF.

2. With slower emulsions (let's say from 200 ISO up), the 'perfect' negatives enlarged to the same dimensions give a clear, obvious, advantage to MF from around 13x18 cm up. These slower emulsions will often be needed for handheld shots at apertures enabling enough depth of field, or even tripod shots of living subjects (portraits, groups, animals for example).

3. To get to that 'perfect' slide/negative, the 35mm gear ought to be used with great care: very high end optics, heavy tripod and MLU on one side, extremely careful processing and printing on the other, will generally be needed to milk out that last drop of quality. I find this shooting behaviour contradicts the very essence of 35mm.

4. It is a paradox that MF allows more flexibility than 35mm to get to an equivalent level of quality for a given print dimension: handheld 645 (RFs or modern well dampened SLRs) or 6x6 (RFs or TLRs) and even 6x7 (RFs) or 6x9 (RFs) are possible in loads of circumstances where camera/user vibrations will remain (almost) unnoticeable due to the smaller enlargement ratio.

5. Of course, 35mm allows the usage of super fast lenses (opening up to f1), which might allow the existence of images otherwise impossible, but that is not a 'quality' advantage, it is a (major) functionnality advantage.

6. Managing the 'perfect' negs/slides once they exist is more secure with MF (much lower influence of dust specks or small scratches when printing/scanning), though all the hardware and services associated with that management are much cheaper for the 35mm production.

So, at the end of the day, at the most common enlargement ratios (including typical wall frame dimensions) it seems difficult to justify totally eliminating the 35mm format in favour of MF, even on benchmarkable imaging quality grounds.

I nevertheless think the "best" option is to keep only a small 35mm setup with high quality fast fixed focal lengths (nothing slower than f2.8) for the low light work plus the long teles eventually required, and to concentrate the attention on a good flexible MF setup for 'general' assignements. This gives the user the guarantee that he/she will be able to systematically deliver the best possible results to his/her customers, even if that level of quality will often be an overkill compared to the requirements of those customers.

Alan
Brussels-Belgium

[Ed. note: Maybe we should say microfilm and 16mm cameras are best? ;-) ]
rec.photo.technique.misc
From: [email protected] (Martin Tai)
[1] Minox lens resolution
Date: Sat Dec 05 09:56:48 CST 1998

Minox Ultraminiature Camera lens test

I recently tested the resolution of Minox lenses

Test Chart: Mire-test Chasseur d'images

Film: Kodak Techical Pan 4.5 mil Estar-AH base 150' roll slitted into 9.5mm Minox film.

Developer: Agfa fine grain BW developer Rodinal-Special

The follwoing are the resolution figures.

Minox C , "MINOX" lens 15mm/f3.5 163 line-pair/mm on film.
Minox B, "COMPLAN" lens, 15mm/f3.5 177 line-pair/mm on film

Note: MINOX lens is the lens in C, LX, TLX, and Minox enlarger III
COMPLAN lens also for: III, IIIs, B and Minox enlarger II
COMPLAN has a very slightly curved film plane.

The average of two Minox camera lenses is 170 lpmm.

Base on 320 lpmm resolution of Techpan, the aerial resolution of Minox lens is estimated at about 360 lpmm average

If higher resolution film is used, the on film lpmm will certainly goes up.

With 500 lpmm Fuji HS-U, on film resolution should be 210 lpmm, with 800 lpmm Fuji Super HR, the on film resolution should be 250 lpmm.

With Techpan and Minox enlarger lens, nice 9x12" enlargement can be made.

With Fuji Super HR, nice 12 x16" enlargement can be made from Minox negative.

These enlargements should be able to withstand close scrutiny at 10" distance, if looked at longer distance, bigger enlargements can be made.

martin tai

From: Brian Ellis [email protected]
Newsgroups: rec.photo.equipment.medium-format,rec.photo.equipment.35mm
Subject: Re: 35mm vs. medium format :35mm is equal to MF ?
Date: Mon, 07 Dec 1998

David - I agree with everything you said. However, if you get into 4x5 don't expect to see the same degree of difference between 4x5 and medium format as you see between 35mm and medium format. Like you, I see a clear difference in tonality (not necessarily in sharpness) between an 8x10 print made from a 35mm negative and an 8x10 print made from a medium format (6x7 in my case) negative. However, there is little if any difference between an 8x10 print made from a 4x5 negative and one made from a 6x7 negative. Even at 11x14 it's often hard to see any difference, especially if the 6x7 was made from a medium or slow speed film. There are, of course, other reasons for using 4x5 besides sharpness or tonality (ability to develop different sheets of film differently and the movements available on a 4x5 camera).

David Johnson wrote:

> People can argue all they want about whether 35mm is theoretically
> equal to medium format.  They will also waste their time.  The
> ones claiming 35mm is at least the equal of MF either haven't
> shot MF or haven't shot MF well.  I shoot
> both medium format and 35mm.  For detail and tonality, MF wins
> easily.  To those that say you can only see the difference for
> prints over 8x10, either your vision isn't very good or you haven't
> seen good examples of MF photography.  The difference is evident
> in even 4x5 prints.  If 35mm really were the equal of MF, there
> wouldn't be any MF - not with its higher price, bulk and poorer
> agility.
>
> Rather than argue theory, how about actually shooting and settling
> the issue.  I have using a solid tripod.  I have shot with Leica,
> Nikon (this is still
> my primary system), Minolta, Pentax, Yashica, and Olympus in 35mm.
> I have shot with my Mamiya 645.  For image quality, the Mamiya
> wins hands down.  However, I am not selling off my 35mm equipment.
> I can get many good photos with my Nikon that I could not with my
> Mamiya do to the better handling and faster operation of the Nikon.
> I plan on getting a 4x5 or 5x7 view camera someday.  Larger
> film really does result in better image quality.  Do you think
> Ansel Adams lugged around that 8x10 view camera for fun?
> --
> David Johnson
> XLNT
> [email protected]

From: [email protected] (NYCFoto)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: 35mm vs. medium format :35mm is equal to MF ?
Date: 7 Dec 1998

I would love if 35mm were comparable to MF. And to that end I tested 35mm techpan, at 320 lp/mm the highest resolving and finest grain film there is, to 6x6 tmax 100, which resolves 200 lp/mm. I used both cameras on a heavy tripod, and the same equivalent focal length lens, and shooting the identical subject at the same time.

I then made 11x14 enlargements from both. The MF image was far higher quality than the 35mm image even though the 35mm film was a far higher resolving film. The 35mmm techpan didn't show any grain at all, in fact grain only shows with techpan supposedly at 25x enlargement, but it didn't have the smoothness of gradating tones that the MF had, and wasn't nearly as sharp or resolved as the 120 tmax100.

From Medium Format Digest:
From: Gene Crumpler [email protected]
Subject: Response to How much for a clean lensed Rollei 3.5F?
Date: 1999-01-12

I've been able to produce quite sharp 16x20 B&W prints with my 80mm Mamiya and a 105 chrome that has since broken beyond repair. For my current 80mm black lens, I tested as follows:

F4--     45 lp/mm
F5.6-    48
F 8---   72
F11-     72* optimum
f16-     72
f22-     42

If I stay in the f 8 to f16 range, good 16x20's and beyond are doable.

These numbers compare fairly well with my new p67 lenses, considering that I have $350 in the C33 system and almost $4k in the p67's.

Since from the above you have probably guessed that I am a sharpness freak, I would first test your mamiya lenses, then get hold of a 3.5 planar and perform the same test. That would be my determining factor in the decision to trade or not.

Of course if you don't plan to print any thing past 11x14, then ignore the above.

[Ed. note: it is often not emphasized enough that viewing distance is critical to quality perception, maximum circle of confusion, etc.]

Date: Thu, 24 Dec 1998
From: "Francis A. Miniter" [email protected]
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Circle of Confusion

The circle of confusion has nothing to do with optics - except those of the human eye. The question is simply what size of blob will appear to the average human eye to be a point from any given distance. That has not changed in fifty years or even longer.

The generally accepted formula is as follows:

C = (v * D)/(1000 * S)

where C is the Circle of Confusion

v is the film format size (any rectilinear dimension in mm, e.g. 24 mm on 35 mm film
D is the print viewing distance (all in mm, e.g. 250 mm)
S is the print size (you have to use the same rectilinear dimension used for v,
e.g., 192 mm on the 8" side of an 8x12).

So C = .03 mm for an 8x12 enlargement from a 35mm negative to be viewed at 10 inches. The print viewing distance is the subjective element. For an 8x10, the standard viewing distance is accepted as 10 inches, or 250 mm. (I know plenty of photographers who take off their glasses and examine a print at about 1 inch, however.) For a 20x30 print, you would have to stand much farther back just to see the full print, and so the circle of confusion will be larger, since you will be farther away.

EDGY01 wrote:

> In the formula for Depth of Field one of the  variables is the "permissible
> diameter of the circle of confusion."  In today's  modern optics (with
> substantial correction), what is the diameter that a  lens manufacturer uses
> when they lay down the depth of field marks on their  lenses?  In other words,
> what has become known as an "acceptable range of  sharpness?"  (Fifty years ago
> we were talking a circle of a diameter of 1/250th of  an inch).  Any definitive
> information out there today?
>
> [email protected] 

From Nikon Digest:
Date: Mon, 25 Jan 1999
From: Jim MacKenzie [email protected]
Subject: Med. format lenses on Nikon 35mm [v04.n214/8]

Mark Parsons, all:

This is getting off-topic, so this will be my last post on the list about this subject.

Regarding the debate about medium format lenses and 35mm bodies...

Mark argued that medium format lenses by definition must have the same or better resolution than 35mm lenses, or else photographs made with them would be less sharp; results show that they are sharper.

This is not true.

Why?

1) Medium-format images use larger negatives. This results in less enlargement to get the same print size as 35mm film. As a result, film grain plays a much lesser role in image quality. I think you would all agree that shots on a really good quality, low-grain film are sharper than shots on a faster, high-grain film. (I know some people think that images shot on, say, Tri-X seem sharper than images on slower films, but examine the image under magnification. The sharpness of grain can give the illusion of image sharpness, but if you examine the image carefully, you will notice that the image sharpness [e.g. really fine detail] is not as good.)

2) Medium-format images, because of the lesser enlargement, do not require the same degree of lens sharpness as 35mm lenses because the images are magnified less.

Let us assume that Joe uses his Nikon FM2 and 50/1.8 AI-S to shoot an image. Let us assume that his brother Bob uses his Pentax 67 with 80mm f/2.8 image to shoot the same image. (Perspective with each lens on its native film format is roughly the same.)

Each makes an 11x14" print from his negative. Joe's 35mm negative is 2.4x3.6cm or 8.64 square centimetres; Bob's is 6x7 cm or 42 square centimetres. Notice that Bob's negative is almost 5x (4.86) larger than Bob's.

I realize that cropping will play a role because the 35mm negative does not enlarge perfectly to 11x14", but let us assume that the image is printed in a format that prints the entire negative onto the identical print area. In reality, the 35mm print would be slightly cropped and enlarged even more than this example, making my point even more dramatic.

So ... to make that 11x14" print, which in metric is 27.94x35.56 cm or 993.54 square centimetres, requires:

- 35mm negative - 115 x enlargement
- 6x7 negative - 23.65 x enlargement
This results in a 4.86 x difference, just like before.

So ... even if a 35mm lens had double the resolution of the 6x7 lens (I am assuming resolution would be proportional to the square of the magnification; if my assumption is wrong, then this could be 4x resolution difference and not 2 and still be true), the 6x7 image would still be somewhat sharper JUST BASED ON THE LENS QUALITY ALONE, and totally ignoring the fact that the image is sharper because of improved film quality due to lesser degrees of enlargement.

Don't believe me? Try a test and see. Just remember that if you use 35mm film and 120 film, and use the same emulsion, the 120 film is going to have higher resolution right off the mark (due to lesser enlargement) unless you compare a similar area of film. If you use the same focal length of lens on both cameras (exact focal length - e.g. 85mm on the 6x7 and 85mm on the 35), and examine the same, small piece of detail from each negative, you will be overriding the film differences and you will see that the 35mm image is sharper.

If you want the logical, instead of mathematical, argument, think of this: what's easier to make, a small lens covering only a small image circle, or a larger one covering a large image circle. The larger you make a lens, the larger the pieces of glass become and the harder it is to make them effectively and accurately. (This is also part of the reason why you have 80mm f/2.8 normal lenses on medium format cameras, and 50mm f/1.8 or f/1.4 normal lenses on 35mm - it would be extremely difficult to design a quality lens with an f/1.4 aperture for a medium format camera. Of course, it would also cost $2 million :) ... but that cost is because of the design difficulties. A 50/1.8 lens for a 35mm camera, new, can cost under $100 US and be an extremely sharp optic.)

Hopefully somebody here has an archive of Popular Photography issues and can find that article written a few months ago that discusses this issue, and then you will all believe me.

Jim

rec.photo.equipment.medium-format
From: [email protected] (David L. Glos)
[1] Re: Evolution of MF to MF
Date: Wed Feb 24 07:41:41 CST 1999

>Classic Photo wrote:
>
>> >Very simple.  Nikon 35mm does not produce the quality of images that
>> >Contax/Zeiss produces.  I have had too many Nikon images rejected by
>> >my agencies whereas the Zeiss images are kept.  The new generation of
>> >D  Nikon lenses are total garbage.  Every image is fuzzy.  It is a
>> >real disappointment since the bodies are great but the lenses are
>> >crap.  It just does not work together to produce a high quality image.
>> >I do not need AF. And in my view, D  stands for distortion.
>>
>> This is a serious stretch Gary. I have no problem with your
>> preference for Contax, but many of use use Nikon and Canon
>> lenses on a daily basis, and they are plenty sharp. I
>> seriously doubt most people (especially stock agencies)
>> can tell the difference between an image shot with a
>> Contax, and one shot with a Nikkor or Canon L lens.
>> My opinion of course.
>>
>> >Zeiss on the Hasselblad is not worth the cost compared to the cost and
>> >quality of lenses for the P67 and P645.  And the rectangular format is
>> >much more accepted by the agencies than is the 6x6cm frame.
>>
>> I don't see why it should be any different. I shoot rectangular
>> in MF, so I'm not advocating Hasselblad. But a *lot* of very
>> successful photographers use Hassies without fear of rejection :)
>> If Zeiss glass is worth it in 35mm, it should be worth it in MF.
>> It just seems to be a very contradictory statement.
>
>Sorry but
>    'Zeiss sufficiently-better-than Nikkor/Canon'
>does NOT imply
>    'Zeiss sufficiently-better-than P67 lenses'
>I see no contradiction. You are free not agree with either statement but the
>logic is fine.
>
>Iain

I can't make a meaningful contribution to the Zeiss vs Pentax thread, but I can comment on Pentax MF vs Nikon. After years in the Nikon world, I decided to supplement my 35mm gear with MF, and ended up with a Pentax 645 system. I work in medical research and as such, have access to some nice low magnification (6-50x) stereo scopes. Every time I add a new optic, I always end up running a couple of test rolls that get examined under these scopes. Since I don't have enough dollars for the multi-kilobuck glass, its more a curiosity and weeding out the duds type of exercise. The general consensus has always been the best MF glass is of lower overall resolution than the best 35mm glass, and that may be true. However, I have found my Pentax 645 glass (45, 75 and 150, and just recently the 35 and 55) to consistently equal of better my best Nikon glass (24/2.8 AIS, 35/2.0 AIS, 50/1.4 AI. 85/2.0, 70-150/3.5E, and 180/2.8 AI). The P645 35 and 150 are especially prized. Truth be told, the 35mm needs to be stopped down to f/8 to be razor sharp corner to corner, but even a Nikon 20/2.8 needs to be at f/5.6 to achieve same. The center 2/3 of the image is perfectly acceptable wide open. The P645 150 is somewhere in a realm of its own. Contrast and sharpness are through the roof. The former may have something to do with its rather simple construction (4 elements in 4 groups). The only downside is a somewhat gritty Bokeh. My Pentax glass also seems more flare resistant than my Nikon glass. The Nikon gear still gets a lot of use when I need to shoot faster or longer glass, or just taking some snapshots, but my P645s takes care of the rest. I certainly can't argue that some of the other MF lines offer unique advantages over the P645, like darkslided backs and leaf shutters. But quality of construction and sharpness of their lenses are beyond fault.

Considering the price, size and weight of current pro-level Nikon gear (N90s, F100, F5) and glass, it would not be completely unreasonable to think of a Pentax 645N as a valid option, especially if you don't need fast or long glass.

David Glos

Univ. of Cincinnati
513.558.6930

[Ed. note: MTF of human eye...]
rec.photo.equipment.35mm
From: [email protected] (Michael Gudzinowicz)
[1] Re: MTF of Human Eye
Date: Wed Feb 24 19:37:02 CST 1999

liam [email protected] wrote:

>What is the MTF of the human eye?

  Cycles         LPMM     Relative
  per            at      Intensity
  Degree         250mm

     0.2          0.04         0.07
     0.3          0.07         0.11
     0.6          0.13         0.18
     1.0          0.23         0.28
     1.8          0.40         0.46
     3.2          0.72         0.82
     5.6          1.29         1.00
    10.0          2.29         0.88
    17.8          4.08         0.40
    31.6          7.25         0.13

You might want to plot the values using the log for each axis. The transfer function values are relative to the maximum which occurs around 5.6 cycles per degree. The second column is a conversion of the first to lines per mm observed 250 mm from the eye, comparable to typical print viewing distances.

rec.photo.equipment.35mm
From: [email protected] (Michael Gudzinowicz)
[1] Re: MTF of Human Eye
Date: Sat Feb 27 06:09:27 CST 1999

"Billy R" [email protected] wrote:

>It's unclear as to what your data represent but MTF is not a measure of
>intensity and second, why do you have fractional numbers in the 2nd column
>if it represents the number of line pairs per mm?

MTF values, or in this case, relative optical transfer are a measure of the relative "intensity" (contrast) difference between the minima and maxima of the target compared to the system under test. If you don't feel that these functions measure contrast loss vs frequency, or that those measurements can be applied to determine pattern sensitivity, please explain your conclusions and offer supporting documentation.

In the case of the intact human eye, one usually doesn't insert an invasive probe, but normalizes the response to the maximum sensitivity, in this case, around 6 cycles per degree. To resolve other frequencies as well, the contrast of the target is changed. There are other approaches to how optical transfer functions may be obtained in the psychology literature, and the data on the eye's properties has been around for 30+ years. This table was adapted from a standard text on physiological psychology.

As explained in the paragraph following the table, the lpmm values are a simple conversion of the cycle per degree column assuming a viewing distance of 250 mm. The rationale is the same as that used in lens tests, though with lenses, zero cycles per degree or lpmm is usually the maximum for the function. For a number of physiological reasons, that isn't the case with the eye which has a maximum sensitivty around 6 cycles per degree or a 1 lpmm pattern viewed from 250 mm.

rec.photo.equipment.35mm
From: "Billy R" [email protected]
[1] Re: MTF of Human Eye
Date: Sat Feb 27 11:46:09 CST 1999

Thanks for clarifying your original post. I agree with your description of MTF as a measure of contrast but it is still unclear to me as to whether your table represents empirical or theoretical data.

The eyes contrast sensitivity is usually characterized by the J-shaped modulation threshold curve also referred to as M(t). M(t) represents the minimum modulation required to perceive a sinusoidal target and peaks between 3-5 cy/deg which is the observers visual angle subtended by the target size. This eye-brain response is known as the human visual system MTF. By convention, MTF is defined to be 1 at 0 cy/deg and decreases monotonically with increasing spatial frequency.

Many HVS MTF models exist but the most common ones are from Nill, Schultz, deJong, Bakker and Kornfeld-Lawson. The Army Night Vision Lab eye model is based on Kornfeld-Lawsons model which ignores the low-frequency inhibitory response. Interestingly, if the observer is allowed to adjust the viewing distance, the eyes contrast sensitivity approaches a constant which is called the non-limiting eye MTF or HVS MTF equals 1.

rec.photo.misc
From: Don Farra [email protected]
[1] Re: Commentary on sharpness, a case for medium format and beyond
Date: Mon Mar 15 16:52:26 CST 1999

Good points, but let me put a twist on them and see what comes out.

First, I believe the diffraction is 'a' limiting factor for 35 mm and not as much for medium format. I clearly stated this in the post using examples. I will restate it here, given you want to stop down to gain depth of field per your example. When you do so, the lens limits the upper resolution number that can be recorded on the film, more so than the film itself. Now it is a simple matter of degree of enlargement. If you use the 35 mm negative and want to make a large "sharp" print it will hit a upper limit quicker than a 6x6 or 6x7 negative, using the same film. Not due to the film resolution limitations but the diffraction limit. If anything lenses all fall short of the theoretical diffraction limit.

The reason why diffraction plays such an important role it is the overriding attribute of the lens that limits the system performance of lens and film resolution combination. For example if you stop down to f/16, it doesn't matter if you are using techpan or not, since the lens cannot resolve equal to or beyond the film's capability. This is true no matter who makes the lens or what type of coating is on the lens. The diffraction limitation is the ceiling that cannot be overcome.

In the case of high resolution lenses within the 35 mm system the limitation then becomes the film used. Since the film resolution is dependent on subject contrast to pull the high numbers. And while a lot of 35 mm lenses can pull good resolution number from the center performance they are only as good as there edge performance numbers, likewise for the medium format lenses.

This is why I showed the examples with the 35 mm format. To show that medium format camera is not limited "as much" by diffraction as in the case of 35 mm format. This is due to the fact that the medium format negative does not require the high degree of enlargement compared to 35 mm to achieve the sharp print. That going one step further 4x5 is the best choice, since with the larger film format you can stop down more and still record sufficient information (resolution) that results in a larger "sharp" print.

So it is clear to me that the medium format negative actually performs much better when stopped down, compare to a 35 mm system when the goal is creating sharp prints.

Don

===========

Thomas Bantel wrote:

> Don,
>
> this is an interesting aspect concerning 35mm vs. medium format. But I
> don't believe diffraction is the main factor in favor of the larger
> format. I could even argue, that for classical landscape shots, with
> a very large DOF from near to infinity, there is no real advantage
> to the bigger format. You need to stop down more to get this DOF with
> the longer focal lengths, used to have the same angle of view than with
> 35mm format. OTOH, you have to enlarge less. The two effects will cancel
> out. For other types of shots, both formats shot with the same aperture,
> medium format has the advantage you claim.
>
> IMHO, there is a much bigger advantage of medium format, which shows in
> those crisp and contrasty medium format shots with an amazing amount of
> detail. Lenses and film may be able to resolve 200 lp/mm. But, the
> resolved detail lacks contrast, the MTF of both film and lenses at these
> resolutions is very small. With medium format, the same resolution on
> the same size print will "only" need 100 lp/mm. Medium format will
> need half the lp/mm resolution on film as 35mm format for any print size.
> Now, medium format lenses *might* have a lower MTF than 35mm lenses at
> 60 lp/mm. BUT, if you compare the MTF of a medium format lens at 30 lp/mm
> to the MTF of a 35mm lens at 60 lp/mm, my bet will be on the medium format
> lens. The same goes of course for the film. It's MTF is much higher at half
> the lp/mm.
>
> This seems to be a much bigger limitation for 35mm format to me than the
> diffraction argument. The 1000/(f stop) lp/mm as a limit seem also to be
> a little pessimistic, AFAIK it's more like  1500/(f stop). And an excellent
> lens like e.g. the Canon 300 f/2.8L comes pretty close to this limit, even
> at f/2.8, which would make for more than 400 lp/mm, easily more than most
> films can resolve.
>
> Thomas Bantel  

rec.photo.misc
(1)+-(1) From:[email protected] (Robert Monaghan)
[1] Re: Commentary on sharpness, a case for medium format and beyond
Date: Tue Mar 16 00:42:25 CST 1999

I also like Roger Hicks and Frances Schultz's books - currently enjoying their film book - but their medium format handbook is excellent ;-)

I have also gathered some related notes on medium format versus 35mm and 4x5 LF - based on Harris' work, which suggests that there is an "enlargement gap" between 35mm (14x), 6x6/MF (12x) and 4x5/LF (9x) that limits the critically sharp degree of enlargement possible with 4x5 to about half of what you would expect to get in benefits over 6x6cm simply by geometry alone. Granted, there are other benefits of tonality and grain to 4x5, but from a convenience, shooting, and ease-of-use and film cost perspective, you rarely need 4x5 over med fmt for most reasonable sized enlargements... see http://www.smu.edu/~rmonagha/mf/mfbest.html

on the other hand, I have a "How Much Lens Quality Do You Really Need?" Page at http://www.smu.edu/~rmonagha/third/quality.html

About 99% of all prints are 8x10 inches or smaller prints from 35mm. For a lot of these folks, they only do 4x6 or 5x7 enlargements, and so they don't really need the very best lenses available for such work. The slight difference in lpmm sharpness (center/edge) between the better third party lenses and the best OEM (nikon, canon, pentax) and even Zeiss/Leica lenses is only 10-20% (from say 70-80 lpmm on film to perhaps 85-90 lpmm with the OEM and highest $$ lenses) - for which you see cost increases of 150% to 300% plus.

By contrast, switching format to a 6x6/7 TLR or SLR results in much greater gains than switching from third party to OEM and high end 35mm big-name lenses, simply from the format and image area factors.

as for diffraction, see my notes at:
http://www.smu.edu/~rmonagha/mf/diffraction.html

however, there is a problem with depth of field tradeoffs and medium format versus 35mm (again, see http://www.smu.edu/~rmonagha/brondof.html)

chris perez and others have tested a number of sample med fmt and lg fmt lenses - see http://www.hevanet.com/cperez/index.html

one of the issues identified by Chris Perez et al and in my mfbest.html pages is the issue of film flatness - this works opposite diffraction and is most limiting with fast lenses and wide open - hence the usual wisdom that f/8 and be there ;-) is a good compromise between flatness and focusing error issues (wide open) and diffraction (f/11-f/16 in 35mm etc), although you do have to individually evaluate each lens ;-)

Perez's companion article notes that for $10-25 you can buy a Kodak special 620 style camera which has amazingly good results for the $$, and easily blows away results from 35mm SLR pro gear costing 200 times the $$ ;-)

My conclusion was also that medium format offers a surprisingly low cost and high quality option compared to investing large amounts in 35mm SLR lenses and pro gear which are effectively operating near their lpmm and sharpness limits on 11x14 inch prints. If you do 11x14 or larger prints, you owe it to yourself to take a longer look at medium format

(see my Budget Guide to Medium Format at http://www.smu.edu/~rmonagha/mf/budget.html)

finally, as Chris Perez's article http://www.hevanet.com/cperez/bw/house.html photography on the really cheap shows, you don't have to spend big $$ to get into medium format.

my own Top Ten Myths of PHotography notes that a 6x7 pentax system costs less than an equivalent Nikon 35mm SLR system for similar lens systems ;-) see http://www.smu.edu/~rmonagha/brontenmyths.html

finally, the handling of a medium format SLR or TLR is much closer to using a 35mm SLR or RF than using most 4x5 cameras (including my calumet ;-) A typical medium format SLR kit is not a lot heavier than most of my 35mm pro SLR kits (albeit without motor drive and zooms but all prime lenses).

We could also get into the prime versus zooms issues on sharpness (I have, at http://www.smu.edu/~rmonagha/third/primes.html) but I will give a hint that you don't find many zooms in medium format on how it turns out ;-)

in short, many 35mm users are selling themselves short (and for higher $$) by limiting themselves to just 35mm, and ignoring the benefits of low cost medium format options that could really make major improvements in their larger prints and slide presentations ;-)

hope this is of interest -regards to all - bobm

--
* Robert Monaghan POB752182 Dallas Tx 75275-2182 [email protected] *

[Ed. note: some interesting points regarding APS vs. 35mm...]

From: "Michael K. Davis" [email protected]
Newsgroups: rec.photo.equipment.aps,rec.photo.equipment.misc,rec.photo.equipment.35mm
Subject: Re: APS/35mm lens sharpness tests
Date: 23 Jan 1999

Hi!

Andrew Severino [email protected] wrote:

: On the SLRs, wouldn't the fact the lenses are designed for 35mm also  produce
: better images on the APS format?

No. The resolution and contrast delivered by the lens would be the same.

: I would guess the lens would provide for better definition as the edges are
: not used to lay the image on the smaller APS.  

If you mean to say that the corners of the APS frame are closer to the center of the image circle projected by the lens, and the very same lens is being used for both APS and 35, then there would be some improvement in corner resolution and contrast. The effects of diffraction and the loss of image quality due the greater magnification necessary to reach a given print size would negate this benefit in a hurry.

You say you are content with 12x18's made with Fuji400. Use that same APS negative to make an 8x12 print and you'll almost have the quality of 35mm at 12x18. Diffraction is the untold story that hurts APS the most. It's bad enough with 35mm. Assuming you used the entire width of the APS negative to make your 2:3 aspect ration enlargement, the dimensions of the image area were 16.7mm x 25mm, with a diagonal of 30.1mm. This is just over 2/3 the diagonal of a 35mm's 24x36mm frame -- 43.27mm.

Using this formula to calculate the aperture at which the effects of diffraction become visible (where the Airy disks will be 1/175-inch diameter in a 10-inch diameter print) on ANY size print viewed at a distance equal to the print diagonal:

f-number = Format Diagonal mm / 2.3692

We can calculate the following diffraction limited apertures:

Format      Diagonal   Aperture at which diffraction becomes visible

APS  2:3    30.1mm     f/12.7   (f/11 is the smallest usable aperture)
APS     4:5    26.7mm     f/11.2    f/8 is the smallest usable aperture!
35mm    4:5    38.4mm     f/16.2   f/11 is the smallest usable aperture
35mm    2:3    43.3mm     f/18.3   f/16 is the smallest usable aperture
6x4.5cm 4:5    66.4mm     f/28.0   f/22 is the smallest usable aperture
6x6cm   4:5    70.3mm     f/29.7   f/22 is the smallest usable aperture
6x7cm   4:5    87.1mm     f/36.8   f/32 is the smallest usable aperture
6x9cm   4:5    88.0mm     f/37.1   f/32 is the smallest usable aperture   
4x5in   4:5   153.7mm     f/64.8   f/64 is the smallest usable aperture
8x10in  4:5   310.6mm     f/131.0  f/128 is the smallest usable aperture

So, the smaller the format diagonal, the more vulnerable you are to the effects of diffraction. Why? Because it's the actual diameter of the aperture itself that makes the difference and since smaller cameras have shorter lenses to produce a given perspective, the focal length divided by 5.6, for example, gives us a smaller f/5.6 for APS than the f/5.6 for 35mm. If you don't think diffraction is all that bad, have a look at images made with pinhole cameras. A pinhole suffers from only one aberation -- diffraction. No manufactuer can engineer away the effects of diffraction. Every lens suffers equally as the aperture diameter decreases.

When you crop a 35mm negative to produce a 4:5 aspect ratio print, the diagonal of the image area is reduced and thus diffraction increases for a given choice of perspective.

People like to point out that depth of field improves with a decrease in format diagonal, but this depth of field advantage can not be exploited because of the competing phenomenon of diffraction.

The 6x7 format can use f/32 without visible diffraction effects, but has the same depth of field at f/32 as a 4x5 camera does at its diffraction limited aperture of f/64 (before using movements to reposition the focus plane.) There's a big difference between a 15 second exposure at f/32 and a one minute exposure at f/64. Gee, I wish that wind would back off for just a little bit...

An 8x10 has to go to its diffraction-limited aperture of f/128 to get the same depth of field as the 6x7 format's f/32. 35mm can get the same depth of field at f/16, but will have twice the diffraction in a 4:5 aspect ratio print at that aperture! 35mm must open up to f/11 to reduce its diffraction to that of a 6x7 at f/32. 35mm simply can not enjoy its small format detph of field advantage, and obviously, neither can APS.

At f/8, the smallest aperture APS can use to produce a 4:5 aspect ratio print without visible diffraction, the depth of field will be equal to the 35mm's depth of field at its diffraction-limited aperture of f/11. Notice that's EQUAL to the 35mm, not better, as some APS enthusiasts like to point out, when ignoring the effects of diffraction.

Enjoy the advantages of APS, but do not expect image quality to equal that of 35mm. Any such claims are simply incorrect. If image quality is what you are after, consider 6x7. At f/32, 6x7 offers a perfect compromise in avoiding the diffraction suffered by smaller formats (including 6x6) and the the long exposures necessary to get the same depth of field from larger formats.

Mike Davis

: This fact with the better stiffer base and very fine grained films should
: make the quality of APS at least as good to 35 MM unless maybe you make
: 20x30" posters.
:
: The enlargements I made up to 12x18 on 400 asa are very very nice even  using
: Fuji400 or B&W from Kodak.
:
: The drawback I still see so far on APS is the processing and lack of
: experienced people at it.  Hopefully this is going away with increased
: popularity.
:
: Andrea Severino
: [email protected]

--
/---------------------\
Michael K. Davis
[email protected]
MIME Attachments OK
\---------------------/

Date: Fri, 2 Apr 1999 14:37:46 -0900 (AKST)
From: "Lehman John A." [email protected]
Subject: [Rollei] Rollei T for sale

For Sale, Black 'T' with case, cap, meter, manual, 16-exposure fitting. A late model 1 (with adjustable pressure plate). Camera is clean except slight brassing on takeup spool button, some wear on top of nameplate, and leather scuffed on takeup knob. Meter works in bright light but not in dim. Case has some scuffs -- one reason the camera is clean :-) and some bad thread. Scale is in meters. Shutter speeds test accurate with an electronic tester. $300 or best reasonable offer.

The following are my lens test results with an Edmond Scientific USAF chart, Ilford Pan F+ and PMK:

f stop      Ctr Edge
3.5         66  42
5.6         84  42
8           94  42
11          75  59
16          75  59
22          66  59

Date: Thu, 29 Apr 1999
From: "Kerry L. Thalmann" [email protected]
Subject: Re: homebrew KO 135mm lens Re: [KOML] Kiev lenses

John J Stafford wrote:

> Uh oh, here we go with another famous thread. :)

Hi John,

I didn't mean to start something, but when my mind becomes engaged, there seems to be no stopping the fingers.

> A tidbit or two of
> my own.  First, manufacturing outstanding lenses is very, very
> expensive,
> and smaller lenses (to a point, of course) are less expensive to make
> than larger ones. Rare earth element (blended) glass is about 200 times
> more expensive than regular optical glass. Grinding, finishing and
> coating
> the lenses is also very expensive. Scale in this case is everything.
> If they made an uncompromising medium-format lens, could anyone afford
> it?

I agree with everything you said except the very last sentence (actually, more about large format lenses than medium format since that's where most of my experience is). In many cases, large format lenses (and even medium format in general) are much simpler designs than current 35mm designs). For instance, there are no large format zoom lenses or large format lenses with internal focusing. Also, many large format lenses are quite small and consist of few elements. Also, large format lenses are very simple mechanically. Yes, they usually come mounted in shutters, but the shutters aren't very high tech, changed little in basic design in the last 50 years. In general, large format lenses don't come in helical focusing mounts, nor do the wide angles need to be designed to clear the mirror present in 35mm and medium format cameras. It's not really fair to compare a complex 35mm zoom to a simple large format normal, but that's part of my point. There are several factors that should make the complex 35mm lens cost a lot more than a simple large format optic. What it really all comes down to is economies of scale. In consumer photographic products these days, innovation is driven by the 35mm format, and the new technology may eventually trickle it's way up to medium format and maybe large format. Autofocus, auto exposure, auto film advance and rewind are all very common in 35mm and becoming more common in medium format. Same goes for lens design. There's a ton of 35mm zooms available in just about every focal length range for any camera mount. There are a couple medium format zooms on the market, and none in large format. Same goes for the use of aspheric elements and exotic materials like flourite. These things first showed up in 35mm and are trickling up to the other formats. One reason, as you pointed out is that of the scale. Aspheric elements are in general smaller in the smaller formats (if doing an apples:apples comparison of fixed focal lengths lenses - forget the zooms for now), but the real reason these things show up first in 35mm is the knowledge of the manufacturer that their up front design and manufacturing costs needed to take advantage of this new technology will be easily recovered by spreading the cost over the huge volumes of lenses they will sell in this format. The volumes of lens sales are much less in the larger formats, so the designers either have to wait for the technolgy to trickle up, or risk of ton of R&D money with no guarantee they will be able to price the lenses reasonably enough to sell enough of them recover their costs.

> A better question is would anyone NEED it? As you pointed out very well,
> the answer today is No, we don't need it. We can't image it to the film
> plane with the potential resolution.

Agreed. As long as we use film to record images, there is little point in having lenses that far exceeed the capabilities of the film. Consumer digital imaging technology is still in its relative infancy, but remember when a 4.77MHz PC with 64K of memory and a 10MB hard drive cost $4000? I do (I have one out in my garage). Trust me, in the grand scheme of things, it wasn't that long ago. It is amazing how fast solid state technology has evolved in the last 10 - 15 years. The improvements in density and speed are mind boggling, and the cost of entry has been been constantly driven down as the technology improves (I'm amazed at the computing power you can get for less than $1000 these days). Consumer digital imaging is today a lot like the 4.77MHz PC out in my garage (OK maybe it's more like an 8MHz AT). Imagine what it will be like in 10 - 15 years. I'm not saying film will be obsolete in 15 years (anybody remember those funky black vinyl record albums - show one to a 15 year old today and they'll think it's a Frisbee), but I would be surprised if consumer digital imaging has not overtaken film as the medium of choice for most applications. I will also be suprised if there are not reasonably affordable digital cameras capable of storing images at higher resolution than today's best films.

I'm not trying to start a digital vs. film war here, just pointing out that the current limits imposed by film technology may someday be obliterated by a newer technology. Maybe it won't happen in 15 years (imagine the egg on my face), maybe it will take 50 years, but I'm confident it will happen. Then maybe those 400 lpmm aerial resolution numbers I have been reading about will actually have some meaning in the real world.

> For the sake of economy, yes! Take a look at some of the military
> and high-end aerial lenses. They are long lenses (typically, the film
> format
> they shoot is 5 to 9 inches wide, varying vertical dimensions) and are
> made to shoot wide open _only_. (The specifications for geo survey
> cameras
> require this. Their testing brief states that regardless of the
> existence
> of a diaphram, they will test all lenses wide-open and many serious
> recon work is done with lenses wide open. Ever used a 500mm F5.6 lens
> with 9x9 film? Very strange on land.)

Well, that is certainly a specialized case. Take a look at what the military pays for those lenses (then go out and buy them on the surplus market for $50).

> Good point to keep in mind when we read tests that use the aeiral
> focusing metrics. It is absolutely the wrong way to test the lens.

Well, it is a valid way to test a lens, but a poor way to test a system (I know, semantics, sorry).

Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://www.thalmann.com/

Date: Thu, 29 Apr 1999
From: "Kerry L. Thalmann" [email protected]
Subject: Re: [KOML] Resolution and format.

Kotsinadelis, Peter (Peter) wrote:

> Interesting dissertation.  You sound like a student of Kingslake.

Hi Peter,

Well, I do have a copy of Kingslake's book, but I have never actually taken a class from him.

> What you
> say is accurate, but the reason for the large format lenses being better
> stopped down does apply as well.  In fact, Kingslake points out that all
> lenses are best at about 2 stops down from wide open.

Actually, the 2 stops down from wide open rule of thumb for maximum sharpness isn't as universal as it was just a few short years ago. Many modern 35mm lenses are sharpest wide open (I have seen aerial resolution data to support this, but if you can't get it on film, so what). It also depends on what you mean by sharpest aperture. Many lenses will be sharper in the center of the field for wide stops, but will require stopping down to sharpen up in the corners. The best compromise will be somewhere in between. Perhaps this will be two stops from wide open, perhaps not. Depends on the lens. Most large format lenses have a maximum aperture of f5.6, but this is generally just used for focusing and composing. These same f5.6 lenses may likely be sharpest in the center of the field when stopped down two stops to f11, but to get the maximum overall sharpness corner to corner, most require stopping down 3 - 4 stops from wide open (f16 - f22).

> The loss of
> definition caused by diffraction at very small apertures is more  serious in
> small format because 1/20mm in a small negative is far more significant  than
> 1/20mm in a larger negative.  Thus the diffraction effect at F/32 might
> seriously affect the definition in a small format, but photos made at that
> aperture would be quite acceptable in a larger format.  Also, longer focal
> lengths suffer from chromatic abberations so there is another design
> consideration that needs to be looked at for resolution.

Agreed on both counts.

> I disagree with your comment about Large Format lenses being designed  to be
> sharp corner-to-corner.

I think you misunderstood what I was trying to say. Perhaps I was not very clear. I was not saying that large format lenses are designed sharper corner-to-corner than smaller format lenses. What I was trying to say is that to get an apples:apples comparison between a medium format lens and a large format lens (when the goal is to shoot both on the same format), you need to look at the resolution at the same distance off axis. In other words, this discussion was started when Robert Monaghan recommended using a 135mm large format lens to shoot 6x7. The point I was trying to make is that if you wish to do so, you will only be using the sweet spot in the center of the large format lens' field and never reach the farthest margins of the lenses coverage. That still didn't sound too clear, let me try again. All the resolution numbers Chris Perez has posted for the lenses we have tested, assume that lens will be used on the format it was designed to be used on. In other words, all the large format lenses were tested on 4x5 sheet film and the corner resolution numbers listed are at the corner of a 4x5 sheet of film. The Mamiya 6 lens, it was tested on 6x6 and the corner numbers reported were measured at the corner of the 6cm square piece of film. To accurately compare a large format lens to a medium format lens, when the goal is to use them both on medium format, the only way to get a valid comparison is too measure the resolution of both lenses at the same physical point on the film. I was never intending to say the large format lenses were designed to be sharper corner-to-corner, just that their corners are further from the center. I just didn't want people to think the number I presented comparing the Mamiya 6 lens to the large format lenses could be compared directly, column for column, to accurately assess how the large format lenses will perform when used on medium format. To do so, you really need to compaer the "corner" numbers for the Mamiya 6 lens to the "mid-point" numbers for the large format lenses.

> IMHO, the closest one can come to a so-called "perfect" lens is a
> Biogon-type for wide angles, Heliar or Planar-type for normal lens and
> telephoto.  Theses lenses were designed to be excellent  corner-to-corner at
> wider open apertures (BTW, a Super Angulon is a Biogon-design) but it may
> not be as sharp at the center as other lenses once they are equally stopped
> down.  This is due to design, not format.

I agree with the overall point you are making, and I never meant to imply that the resolution was a function of the format (at least not from the standpoint of comparing lens resolution, lpmm is lpmm regardless of film size). I do mildy disagree with your assertion that the Biogon types are the closest to a perfect lens in the wide angle arena. Advancements in the design and manufacture of lenses employing aspheric elements is starting to give us some lenses that perfom better than the old standards. It will be intersting to see how this trend progresses. Also, whether a lens is excellent corner-to-corner wide open may not be all that important, depending on the application. When shooting three dimensionsl subjects it is often necessary to stop down several stops to get the desired depth of field, even if your camera has the ability to do camera movements. That's the basis for my comment about most large format lenses are rarely shot wide open (at least not for general purpose photography, there are obvious exceptions like aerial mapping and reproduction work of two dimensional originals).

I don't think we really disagree on much of anything here, it sounds more like a misunderstanding. I tried to explain what I meant to say in the previous post. Hopefully it was clearer this time. If not, well, then for the next round, I'll have to break out the visual aids. The old cliche about a picture being worth a thousand words seems to apply ten fold when discussing the process of making pictures.

Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://www.thalmann.com/

From: "Kotsinadelis, Peter (Peter)" [email protected]
Subject: RE: [KOML] Resolution and format.
Date: Thu, 29 Apr 1999

Kerry,

Good thread! Now I understand what you are saying and I think we are in agreement just saying the same thing a bit differently. As to the perfect lens, it is a subjective matter. To Kingslake it was the Heliar, to Rudolph it was the Planar, and for microscopes to this day its the Petzval. It will vary based on need and sometimes format. It is much more difficult to correct the problems associated with abberations in a particular design as you increase the aperture. This is one of the reasons that the Tessar was never a real high-speed lens, Zeiss left that to the Sonnar design which they had as a 50mm F1.5 sonnar in the early 40s. If you trace back any of the lenses you use for medium or large format to a design, it may go back several times. A Schneider Super Angulon is really a Biogon-type design as is the 58mm (or 60mm) KO/RO Lens. Are they perfect? No! But then again no lens is. The Biogon design is considered by many (I've learned to never say all) to be the finest design in a wide-angle lens. This design/lens was the lens sent into space (Zeiss 38mm F4.5 Biogon on a 'blad) aboard Gemini 9 in 1966. The same lens, modified by Zeiss with special optics for use in space went to the first manned moon landing, a 60mm F5.6 Zeiss Biogon.

Peter K

>I do mildy disagree with your assertion that the Biogon types 
>are the closest to a perfect lens in the wide angle arena.  
>Advancements in the design and manufacture of lenses 
>employing aspheric elements is starting to give us 
>some lenses that perfom better than the old standards.  
>It will be intersting to see how this trend 
>progresses.  Also, whether a lens is excellent 
>corner-to-corner wide open may not be all that important, 
>depending on the application.  When shooting three 
>dimensionsl subjects it is often necessary to stop 
>down several stops to get the desired depth of field, 
>even if your camera has the ability to do camera movements.  
>That's the basis for my comment
>about most large format lenses are rarely shot wide 
>open (at least not for general purpose photography, 
>there are obvious exceptions like aerial mapping and 
>reproduction work of two dimensional originals).

Date: Wed, 28 Apr 1999
From: "Kerry L. Thalmann" [email protected]
To: Koni-Omega Mailing List [email protected]
Subject: Re: homebrew KO 135mm lens Re: [KOML] Kiev lenses

Lyndon Fletcher wrote:

> First it is my understanding that in terms of resloved lines per mm the
> relationship is 35mm > MF >LF. I understand that LF lenses are not as well
> corrected at MF lenses of approximately the same focal length. Why this is
> I don't know but that was always my understanding. Kiev lenses are MF and
> the Zork site indicates that SOME of them are capable of 6x7. Wouldn't
> these lenses be better corrected than a LF lense?

Hi Lyndon,

I'll address just the first part of your post (since that's an area where I have a little first hand experience).

The assumption that resolution (in line pairs per millimeter) is higher for 35mm lenses than medium format lenses than large format lenses is partially based on fact, partially based on old wives' tales, and partially the result of stale data. In theory, an ideal lens is sharpest wide open, and you lose resolution to diffraction progressively as you stop down to smaller apertures. In actual practice, we don't work with ideal lenses. Real world lens designs have certain uncorrected aberrations that improve as you stop down. The extent of these aberrations, and how much they improve as you stop down is a function of the individual lens design. So in the real world, you stop down to correct these aberations, but eventually run into the diffraction limit. That's why most real lenses aren't sharpest wide open, nor are they sharpest fully stopped down. The general rule of thumb I often hear is "sharpest 2 - 3 stops from wide open). In general, for most 35mm lenses, that's probably not too terribly inaccurate, but it does vary from lens design to lens design. Most large format lenses are optimized to be at their sharpest (corner to corner) at f22, some at f16. This again, is a rule of thumb and not absolutely accurate for all large format lens designs.

So, on paper, given the assumption that ideal lenses are sharpest wide open, the advantage would appear to go to the smaller format optics. This ignores one very important consideration. This is only for the aerial resoltion of the image produced by the lens. In the real world, we use film and cameras to record this image. In other words, we make images with a system, and the lens is just one part of the system. I have seen some incredible numbers for the measured aerial resolution of modern 35mm lenses (numbers in excess of 400 lpmm). Far in excess of the capabilities of current film technology. So, the small format lens may be able to resolve more, but we aren't capable of capturing it. Chris Perez and I have tested several large format lenses, and a smattering of medium format optics. Although the current large format optics do not yet appear to the point of exceeding the resolving power of current films, under ideal conditions, they come darn close (a lot closer than I had thought they would before we started conducting our tests). We haven't tested any 35mm lenses, but I have followed the work of others. In general, it is very rare to see a published report of resolution higher than 100 lpmm for any 35mm lens USING ON FILM TESTING METHODS (sorry to shout). Occasionally, I will see something in the 120 - 140 lpmm, but in those cases the tester is usually using Tech Pan film, an ultra high resolution film that is not generally used for pictorial use. With the commonly used, finest grain pictorial films, 100 lpmm is about the best out there right now. To put that in perspective, here's a few numbers from the sharpest medium format and large format lenses we have tested to date (the resolution numbers are center, mid-point and corner):

Medium Format:

Mamiya     6 MF  75mm f/3.5             f3.5 76 76 53
                                        f4   76 67 53
                                        f5.6 95 76 53
                                        f8   95 85 53
                                        f11  85 85 60
                                        f16  76 67 67
                                        f22  60 60 53

Large Format:

Nikon      SW f/8 90mm                  f11  80 80 60
                                        f16  67 67 60
                                        f22  60 54 54

Schneider  Super Symmar XL f/5.6 110mm  f11  80 67 60
                                        f16  67 67 67
                                        f22  60 60 60


Rodenstock APO Sironar-S f/5.6 150mm    f11  76 85 43
                                        f16  76 76 43
                                        f22  60 60 48

Granted this is a very small sample size, but here's a couple observations. At first glance there seems to be a slight edge for the medium format lens. It hits resolution numbers as high as 95 lpmm center and has a best overall score of 85, 85, 60. None of the large format lenses posted a number higher thn 85 lpmm, with 80 lpmm being the typical highest center resolution for the best of the large format lenses tested. The best overall score was 80, 80, 60. Two things are deceptive here. First, while there is no disputing the center resolution numbers, there is a difference in the location of mid-point and corner for the different film formats. For example the corner numbers for the medium format lens only lie about 1.5" from the center. In the 4x5 tests, the "corner" is much further from the center of the film area, about 3.3". So, in reality, to do an apples:apples comparison, we should throw out the corner numbers from the large format results. Afterall, the mid-point on the 4"x5" film is actually further off axis than the corner point on the 6cmx6cm. So, now the best of the large format lenses are capable of around 80 lpmm corner to corner when shooting them with medium format film. I like to think of this as using the sweet spot in the center of the lens' image circle. Most lenses are sharper in the center of the field than off axis. The resolution generally tapers off gradually as you move off axis. When using lenses designed for large format with the smaller format film you never really get far enough off axis to reach the point where the resolution starts to taper off significantly.

The second observation, and this is just a hunch, is that we may not even be seeing the "best" resolution that the large format lenses are capable of due to the way we conducted the tests. If you notice, all three of the large format lenses listed above have their best center and mid point performance at the maximum aperture tested (f11). In general, the center and mid-numbers go down, but the corner numbers go up as you stop down from f11 to f16 to f22. We expected this behavior before starting these experiments, so we didn't bother testing wider than f11 (besides, in large format, for various reasons, you rarely shoot wider than f11 anyway). Perhaps some of these large format lenses would be even sharper center and mid-point at f8 or f5.6. They would likely be soft in the corners of 4x5 at these wide aperatures, but if you're intending to use then on 6cmx7cm, that may not be an issue.

That was a lot of typing, and doesn't really prove anything beyond a shadow of a doubt (there really isn't enough eveidence to draw an irrefutable conclusion). I just wanted to point out, IMHO, that the differences in on film lens resolution between the various formats is not as great as commonly accepted. Specifically, will the Kiev MF lenses be sharper than LF lenses of comparable focal length, I don't know. It really depends on the designs of the lenses in question and the quality control during manufacturing. Best to test them before drawing any conclusions. BTW, I was not volunteering to test any Kiev lenses. We did test several KO lenses Monday night (3-58s, 3-90s, 1-135 and 1-180). Chris will post the results as soon as he soups all the film and reads the negs. Since the KO lenses are of similar design, and have a reputation of excellent quality control, I would expect them to perform in the same ballpark as the best LF lenses of similar vintage. We'll know for sure in a few days.

Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://www.thalmann.com/

From Nikon Mailing List:
Date: Wed, 2 Jun 1999
From: Martin Giphart [email protected]
Subject: RE: [NIKON] How Sharp is Sharp?

Dear Nikonians,

Dennis Schuchman [email protected] wrote:

> One of the reasons we all use Nikon gear is the legendary optics.  If
> asked if we wanted the sharpest lenses possible, I'm sure most of us
> would say yes.  But how sharp does a lens really need to be?
> It's clear that some photographers are more concerned about sharpness
> than others.
> Some carefully shoot slides and examine them with a high quality loupe
> to check lens sharpness.  Some just buy a lens based on it's
> reputation and go out to shoot pictures, figuring that the lens will be sharp
> enough. I'll admit that I've been tempted to tape newspapers to a wall
> and shoot careful slides and look hard at the results.  But some inner
> voice tells me that all I would determine was whether or not that
> particular lens was suitable for newspapers-tacked-on-a-wall
> photography.
>
> The ramifications of the sharpness issue really influence lens
> selection.  Some people insist on using only prime lenses arguing,
> correctly on the whole, that zooms just can't be as sharp as good
> primes.  Others think that good zooms are sharp enough.  Some
> posters to this list have recently recommended against the new Tamron 28-300,
> knowing nothing about it other than its focal length range, insisting
> that it can't possibly be sharp enough.  At least one responder pointed
> out that the 28-300 will take better pictures than a 300/2.8 that was
> left at home because it was too heavy to drag around and that
> the 28-300 would be sharp enough.
>
> You'll notice that the phrase "sharp enough" keeps cropping up here.
> How sharp is "sharp enough"? Is there an absolute measure of
> it or does it depend on the individual photographer and his or her needs?
>
>
> Ask yourself this question:  How many times have seen a potentially
> great photo ruined because it wasn't shot with a sharp enough lens?

Lately, there seems to be a focus on the subject 'sharpness of a lens', which I think in most cases is of no concern. Thanks to modern technology most lenses are (very) sharp, or for most circumstances sharp enough. It is often said that the ability to distinguish more than 100 lines / mm is not visible to the human eye and therefore is not interesting. In fact the ability to distinguish more than 100 lines/mm is not good for the way the lens handles contrast, in other words: contrast and sharpness are complementary. A good lens offers a good compromise between these two properties. Another point is that the human eye is easily fooled; a lens that in fact is less sharp than another lens, but is capable of handling contrast better is often interpreted as being sharper!

The properties which are far more visible in pictures than the sharpness of a lens are:

- - the way the lens handles contrast
- - distortion
- - light fall-off/vignetting (whatever you like to name it)

I've owned the Tamron AF28-200 mm (the first model), which was quite sharp, but had a lot of distortion in mostly the 28mm-end and was not very good in the handling of contrast full-open (3.8 at 28 mm, 5.6 at 200 mm). The light fall-off used full-open and even two stops closed was noticeble, especially in slides. So, in terms of sharpness it was quite good, but in all other terms it wasn't. These facts, along with the fact that it is a variable-aperture lens, are the reasons most professionals, or people who like to be recognised as such ;) don't like this lens. BTW, the successor of this lens ('Super') is said to be better in all, or most of these aspects.

I know this is quite a difficult subject and there'a a lot that can be said about it. I have an old dutch magazine in which this subject has been explained quite thoroughly. If people are interested I might try to translate it. On the other hand, it must be available somewhere on the web, I guess?

I hope this helps.

Martin Giphart,
The Netherlands.

From: [email protected] (Thor Lancelot Simon)
Newsgroups: rec.photo.technique.nature,rec.photo.equipment.large-format
Subject: This 35mm vs 4x5 myth
Date: 13 Jan 2000

>> Joshua Wein [email protected] wrote:
>>
>> >Why is it that they cannot get the same high resolutions in LF lenses? Is it
>> >some aspect of the physics? They have access to the same design theories,
>> >and the same exotic materials, and as we all know cost is not an issue. Just
>> >curious. The LP/MM differences are quite large it seems.
>>
>> There are always trade offs in lens design.  Since large format doesn't
>> need the same resolutions as 35mm effort is put into other aspects instead.
>
> Rick,
>
> Ok, I'll bite and ask the stupid question.  What other aspects
> are there beside sharpness/resolving power?

The obvious one, of course, is coverage. A typical modern large format lens covers 80 degrees or more at infinity focus, allowing substantial movements (note that this means that a 4x5 "normal" lens almost covers 8x10 with no movements!). Since 35mm cameras typically do not offer any movements at all, 35mm lenses can be optimized over a much narrower angular field, giving higher resolution in the much smaller circle of coverage.

There are some other factors which help explain why large-format lenses (well, actually, the entire lens/camera/film system) have lower maximum resolution than 35mm:

1) For a given lens design, a sample of longer focal length will
   have slightly lower resolution than a sample of shorter focal
   length.

2) Working aperture.  While the newest large-format lenses are
   probably difraction-limited at f/8 or f/11 (at least in the
   center of the field) for depth-of-field and film flatness
   reasons, as well as to increase resolution at the edges of
   the field when using movements typical working apertures for
   4x5 are usually f/22-f/45.  Most 35mm lenses are probably
   difraction-limited at their typical working apertures of
   f/5.6-f/8, so the large format lenses *can't* produce the
   same resolution.

3) Film flatness.  Even in the best holders, unless you're using
   5" or 10" roll film in a vacuum-back film transport (think
   aerial recon cameras -- they do this) the film in your LF
   system will not be as flat as the film in a high-end 35mm
   camera with vacuum or other esoteric pressure plate technology,
   along with tension holding the thin 35mm film flat.

4) Light scattering in the emulsion.  This may not be an issue
   with newer films, but older LF films had thick emulsions and
   lost some resolution due to light scattering.  Interestingly,
   the first thin-emulsion films were large-format rollfilms
   intended for aerial recon/mapping work...

--
Thor Lancelot Simon
[email protected]

[Ed. note: Mr. Thalmann is a noted lens testing expert...]
From: "Kerry L. Thalmann" [email protected]
Newsgroups: rec.photo.technique.nature
Subject: Re: This 35mm vs 4x5 myth
Date: Sat, 08 Jan 2000

TravGlen wrote:

> As an aside to these two morons, I'd like to point out that "Schneider
> Kreuznach" lenses are available to both medium and large format
> photographers, but not to 35mm shooters. There are few, is any, 35mm lenses
> that can touch "Schneider Kreuznach" in any lenses criteria, and certainly
> nothing made in Japan. Incidentally, this is the same company that makes B&W
> filters. Filters that are, by the way, better than 99% of the glass they're
> put in front of. Size counts, anyone of any sexual orientation can tell you
> that.

As one of the two morons you quoted, I thought I'd respond. I agree with your assessment that Schneider makes top notch glass. The 110mm Super Symmar XL is the most amazing large format lens I have ever used. In addition to outstanding corner-to-corner sharpness, it has huge coverage in a relatively compact, lightweight package. It is truly a wonderful lens. I also own large format lenses made by Rodenstock, Nikon and Fuji. They are also excellent performers.

As the one who was arguing the benefits of 4x5 in my previous posts in this thread, I must disagree with your statement:

"There are few, is any, 35mm lenses that can touch "Schneider Kreuznach" in any lenses criteria, and certainly nothing made in Japan."

For example, if you consider sharpness, 35mm lenses are commonly known to be capable of higher resolution than medium or large format lenses. I have seen measured aerial resolutions numbers in excess of 400 lp/mm for the best modern 35mm lenses. In this case, it is definitely the resolving capability of current pictorial films that limits the actual achievable resolution (on film) to about 100 - 120 lp/mm. The best medium format lenses are in this same ballpark. The best large format lenses are about 85 lp/mm center and 67 lp/mm corner. Of course, the slightly lower resolution of the large format lenses is more than compensated for by the much large film area (requiring lesser degree of enlargement and smaller grain size in the final print). Granted, sharpness is just one criterion in evaluating lenses performance, but it is a very important one.

But, don't take this moron's word for it. Please visit the Photodo web site at:

http://www.photodo.com

They have done extensive MTF testing on a number of 35mm and medium format lenses since 1991. Unfortunately, they have yet to test any large format lenses (although they state they will be doing so in the future). The testing is done on equipment manufactured by Hasselblad and the tests are performed by a Hasselblad employee. These are scientific tests done by a skilled operator using very sophisticated test equipment, not just opinion or anecdotal evidence. The results, on a scale of 0 - 5, are a weighted average of 48 measurements at each f-stop (and various focal lengths for zoom lenses). The highest score achieved to date is 4.8 by a Canon EF 200/1.8L USM (a 35mm lens of Japanese manufacture). The highest medium format score, so far, also belongs to a Japanese lens. It is 4.3 for a Mamiya 7 150/4.5 L. The highest rated Schneider lens is the Rolleiflex Schneider Xenotar 80/2.8 at 4.1. A score of 4.0 or higher rather uncommon for the medium format lenses they've tested (about 10%). A score of 4.0 was very common (just over 50%) for 35mm single focal length lenses, but very rare for 35mm zoom lenses (just over 3%). In fact, over 43% of the fixed focal length 35mm lenses tested met or exceeded the 4.1 score of the highest scoring Schneider medium format lens.

So, based on the Photodo tests, 35mm fixed focal length lenses are sharper, in general than medium format lenses. Many of the lenses that did very well are of Japanese manufacturer, including the highest scoring lenses in both the 35mm and medium format categories. I'm not trying to knock Schneider lenses in any way, they are truly wonderful performers. I just wanted to point out that there are other manufacturers, many 35mm and many Japanese, also producing some outstanding optics.

Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://www.thalmann.com/

Date: Sun, 09 Jan 2000
From: "Kerry L. Thalmann" [email protected]
Newsgroups: rec.photo.technique.nature
Subject: Re: This 35mm vs 4x5 myth

Joshua Wein wrote:

> Why is it that they cannot get the same high resolutions in LF lenses? Is it
> some aspect of the physics? They have access to the same design theories,
> and the same exotic materials, and as we all know cost is not an issue. Just
> curious. The LP/MM differences are quite large it seems.

Hi Josh,

Several reasons. Many aberations are a function of focal length. Large format lenses are longer in focal length than their 35mm counterparts. Still, that alone does not explain it. Afterall, the highest rated lens on the Photodo web site is a 200mm lens for 35mm. One big reason is coverage. A 4x5 lens has to cover a much larger area than a 35mm lens. Optimum lens design involves a series of trade-offs, some involving center vs. corner sharpness. 4x5 corners are much further from the center than 35mm corners. Another is diffraction, which reduces overall sharpness as you stop down. To get optimum overall sharpness, center to corner, most large format lenses are optimized for f22 (some for f16). The best modern large format glass is actually pretty close to the theoretical diffraction limits at f22. They might be sharper in the center of the field at larger apertures, but require stopping down to f16 or f22 to sharpen up the corners. Also, f22 is a pretty standard working aperture for 4x5 shooting due to depth of field issues. Most 35mm lenses are achieve best overall performance at approximately f5.6 - f8, where diffraction is much less of an issue.

Although the theorectical (and aerial) differences in lp/mm numbers between 35mm and 4x5 lenses may indeed be quite large, the practical differences are small to non-existant. One reason is the limitations of current film technologies. The actual on film resolution will be lower than the lowest of the lens resolution and the film resolution. On film test results in excess of 100 lp/mm are extremely rare in any format including 35mm, and keep in mind these tests are usually under ideal conditions (in doors, with no wind, two dimensional, high contrast test target, etc.) In the field, with wind, vibrations, atmospheric effects, lower contrast, three dimensional subjects, etc. the achievable resolution will no doubt be lower. Still, the best LF lenses are capable of on film resolution of at least 85 lp/mm center (btw, most 35mm lens tests I've seen only give a single resolution number, I assume it is for the center of the field, but it could be that there isn't much difference between the center and corner resolution due to the smaller field size). So, in practical terms, the large format lens resolution at f16 or f22, may be only 15% lower than the 35mm lens at f5.6 or f8. Given that the 4x5 film is about 400% larger (in linear dimension for standard prints sizes), that 15% difference in resolution isn't that much.

Finally, there are economic issues at work here. The large format market is very, very tiny compared to the 35mm market. A LOT more R&D money gets spent by a lot more companies on 35mm lens design than on LF lens design. A lot of exotic glass types (fluorite elements) and construction techniques (aspheric elements) that are fairly common on high end modern 35mm lenses have barely started to trickle up to LF lenses (the Schneider Super Symmar HM line are the only LF lenses I know of using fluorite, and the Super Symmar XLs are the only LF lenses to employ aspheric elements). And finally, cost is an issue. LF glass isn't cheap, but even the lowest cost lenses from the big four (Schneider, Rodenstock, Nikon and Fuji) are all excellent performers. LF shooters are very particular, and they don't want to go to the trouble and expense of shooting LF only to achieve suboptimum results by using a poor lens. In 35mm, there are several classes of users and lenses to match. There are budget zooms for the casual shooter, moderately priced good performing primes for the serious shooter with limited resources, and very expensive exotic glass for specialized applications and demanding users. The very best glass is expensive regardless of format. If you just look at the very high end in both formats, I could easily turn your argument around and say that cost is not an issue for 35mm lenses. Afterall, the top rated 35mm lens on the Photodo site, the 200mm f1.8 Canon EF "L" sells for $4159 (B&H USA price) and the sharpest LF lens, the Schneider 110 Super Symmar XL is only $2289 (B&H USA price). Of course that is not an apples:apples comparison, but it sure makes the LF lens look like a bargain.

Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://www.thalmann.com/

Date: Mon, 10 Jan 2000
From: "Kerry L. Thalmann" [email protected]
Newsgroups: rec.photo.technique.nature
Subject: Re: This 35mm vs 4x5 myth

Peter Mikalajunas wrote:

> There have been relatively recent advancements in film technology.
> T-Max 100 for B&W and Velvia for Color provide much better grain
> control across all formats.  This allows, in actual practice, the 35mm
> to acheive better enlargements and begins to equalize the formats.

Hi Peter,

I agree, in principal, with what you're saying, but keep in mind, those same fine grained emulsions are also available in 4x5 and 8x10. So, the degree of enlargement has been improved for all formats (and high end fine art digital imaging techniques is obscuring this further). The real question, is what's the limits for each format (highly subjective) and exactly how big are your going to print the dang things.

> Kerry, you have great taste in lenses :-))

Well, since I shoot with lenses from all the big four, it's not so much a matter of good taste, it's just that all current, modern LF lenses are generally excellent (as are several older, and/or lesser known brands).

> If I take the 150mm XL or the 210mm HM and place them on an 8x10, the
> battle is lost for the 35mm.  But, in essence, I am cheating.   The
> normal lens for 8x10 is 300mm.  So, not only have I gone to the very
> top of the line in glass currently available, but gone wide angle as
> well, thus needing less depth of field control through aperture. ( At
> 8x10 the working aperture switches to f/32 or f/64 in most cases.
> However, because I am using shorter glass, I can stay away from
> diffraction limits and use f/16 or f/22.)
>
> Also by using 8x10, I can contact print all day long and never worry
> about film grain.

I've always found the 5x7 format to be a great compromise between 4x5 and 8x10. Those 8x10 lenses you mentioned above, in addition to being very expensive, are also very large, heavy and take huge expensive filters in obscure sizes. Most of the 4x5 lenses I already have (everything except for the 75mm) will cover 5x7. 5x7 cameras are also not much bigger or heavier than 4x5s. The lack of color film, specifically Velvia in my case, has always been the major drawback to the 5x7 format. Black and white films are much more readily available in 5x7 (T-Max 100, T-Max 400, Tri-X, FP4+, HP5+, etc.). I used to dabble a little in 5x7 black and white several years ago, but gave up on the format when I decided to concentrate my efforts on color work.

But, that just changed. I just picked up a slightly used 5x7 Canham with a 4x5 reducing back, and I ordered four boxes of 5x7 Velvia from Robert White in Great Britain. So, within a week, I'll be shooting 5x7 and 4x5 Velvia with the same camera and set of lenses (the 110mm Super Symmar XL, 150mm APO Sironar-S and 210mm APO Symmar should be outstanding on 5x7). I'll probably still shoot 75 - 80% of my work on 4x5, but will pull out a sheet of 5x7 Velvia for those really outstanding opportunities. As an added bonus, I spoke to Keith Canham on the phone today about his rumored 6x17 roll film back for this camera. It's been delayed several times, but he's proceeding with the design work and hopes to have something on the market by the end of the year. So, with this one camera, that weighes less than 6 lbs., I will be able to shoot 4x5, 5x7 and 6x17 with all the lenses I already own.

This probably sounds a little crazy (and I don't deny that it very well may be), to all the people reading this who shoot in the smaller formats. But like I said in my early responses in this thread, there is no one perfect format for all users and all uses. From my point of view, at least I avoided the temptation to move up to 8x10 (which would have also meant a whole new set of very expensive lenses).

> Finally, this discussion has centered on the very newest, most
> expensive lenses around.
>
> Most of us never get to use that glass until it has had at least 1 or
> more previous owners :-)  There is a sizable number of LF users who
> prefer much older glass.  I prefer my 95 year old 210mm B&L protar
> over my 2 year old 210mm APO-Symmar most days.  Is the protar sharper,
> no way, it isn't even coated.

Likewise, almost all my LF lenses have been bought used at considerable savings. Also, this new camera was bought used, but like new, at about 30% less than it would have cost new (and I'll sell my 4x5 Canham to help cover the cost of the new camera).

Your last point is a very valid one. This discussion has primarily centered on sharpness and resolution, but there are many more factors that contribute to making a successful image (just like there are many different definitions of "successful image"). It's all a case of matching the tools to the subject and the photographer's goals.

Happy shooting,
Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://www.thalmann.com/

From Leica Mailing List;
Date: Sun, 19 Mar 2000
From: Paul Roark [email protected]
Subject: [Leica] image quality and format -- 35 v. 120

On Sun, 19 Mar 2000 Erwin Puts wrote, in part:
If we can use a film that has a granularity size and resolving power that is below the enlargement ratio of the Leica negative, I dare to say that there will be no difference in print quality. That would be the case with Technical Pan.

If we look just at grain, then a 35 mm Tech Pan -- with an RMS grain rating of 5 -- would seem to get close to a 120/MF frame of Tmax 100 -- which has an RMS grain rating of 8.

However, depending on how one defines sharpness, the advantage of TP over Tmax 100 might be much less than Kodak's grain (or resolution) claims would indicate. If we look at the MTFs of the films published by Kodak, the Tmax 100 MTF is actually better than that of TP up to at least 100 lines pairs per millimeter. For example, at that frequency, the relative contrast of Tmax 100 is just over 60%, while the relative contrast of TP (developed in Technidol) is about 50%. In short, the Tmax 100 might actually have a perceived sharpness advantage over Tech Pan.

In my last attempt to move my landscape photography to 35 mm from MF, I thought that the computer, with its ability to selectively sharpen the image, would allow me to offset the MTF disadvantage of the 35 image -- a disadvantage caused mostly by the film size differences. Additionally,I decided to move only my wide angle shots to 35 mm. If you compare the Leica 28's MTF to the Zeiss 50 Distagon's, you'll see that the Leica at the edges may win even with the greater magnification required. (MF SLR wide angles' off-axis performances are the format's weakest area, optically.)

However, somewhat contrary to my tests and assumptions, in actual practice the 35 mm shots did not turn out to be as sharp as the MF shots. I think the difference relates to the margin of error that MF has, combined with the fact that in actual practice, as opposed to lab testing, depth of field is usually important. Let me explain.

I think that most would agree that the MF records more detail than 35 mm due to the film size advantage. However, the issue is really whether a viewer can see that difference at the enlargement level that one is targeting. At 16 by 20, my comparison test prints looked very close, although some saw the difference in the fine detail. The extra detail that the MF negative had was simply smaller, even at a 16 by 20 enlargement, than the eye could detect.

However, in real shooting, depth of field requirements of three dimensional landscapes made the negatives of both formats less than perfectly sharp -- unlike the test negatives I'd used in my test comparisons. In the MF shots, however, the reduction of the detail caused by less than perfect focus did not appear to have as much of an impact on the apparent sharpness of the final image as did the loss of detail in the 35 mm images. Perhaps the MF negatives had enough head room to be substantially less than perfect and still look perfectly sharp at 16 by 20. (Perhaps this is one reason the film flatness issue that is so apparent in film testing is ignored by many, if not most, MF shooters.) The 35 mm negative, on the other hand, may not have had that head room -- thus the loss of detail was more visible.

Just my hypothesis, for what it's worth.

Paul Roark
http://www.silcom.com/~proark/photos.html

Date: Sun, 28 Mar 1999
From: [email protected]
Newsgroups: rec.photo.equipment,rec.photo.equipment.35mm
Subject: Repost of Lens Testing Package

For anyone interested in testing the resolution of their lenses, a resolution chart and instructions for using the chart and evaluating the results in terms of lines per millimeter is available for free. Simply go to the following location and follow the directions for downloading and printing:

"http://www.erols.com/johnchap/lenstest/lenstest.htm"

While the charts and instructions are primarily for testing the resolution capability of lenses, the chart setup can be helpful in quantitatively(rather than the typical qualitative) evaluation of one's ability to handhold the camera with different focal lengths and shutter speeds. Further, when using the sharpest lenses on a sturdy tripod, one can also get a good idea of the "images-on-the-film" resolution capabilities of various films being considered for use.

From: [email protected] (CWood 7000)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: MF lenses vs 35mm lenses
Date: 31 May 1999

>However, a lot depends on the quality of
>the lens and 35mm camera manufacturers have gone to great lengths over
>the years to produce better lenses than their rivals. I would say that
>you would find better lenses in the 35mm market than you would for MF
>cameras and so the balance of what is good enough to be called
>"professional" could lie in the 35mm market especially when you consider
>improvements in film grain. How do MF lenses compare to 35mm prime
>lenses from manufacturers such as Olympus, Nikon, Minolta, Pentax, Canon
>etc.?

MF and LF lenses, are for all practical purposes, as sharp as most 35mm lenses.

Some examples of 35mm lenses by Zeiss, Rolliei, Leica, etc., are exceptional in performance. But this performance is usually negated by the small image size. For an excellent discussion of this issue as it applies to MF and LF (also relevent for 35mm) see:

www.graflex.org/lenses/photographic-lenses-tutorial.html

www.hevanet.com/cperez/MF_testing.html

www.hevanet.com/cperez/results.html

Basically, no matter how you cut it, the larger the format, the better the delivered image. The improvements in 35mm films are also now available in MF and LF.

From: "Kerry L. Thalmann" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: MF lenses vs 35mm lenses
Date: Mon, 31 May 1999

Zane wrote:

> Keeping in mind that you really need to compare MF lenses with their 35 mm
> counterparts that are about 1/2 the focal length:  top quality 35 mm prime
> lenses will have more line pairs per mm of resolution and and more contrast
> at a given line pairs per mm value (for comparable f/nos).  However, for
> the same size print, the 35 mm will have to be enlarged twice as much, so
> the lens would have to deliver twice the resolution of the MF lens to get
> the same sharpness print.  They are not usually a factor of two
> better--maybe a factor of 1.5.

Some very good observations by Zane. However, based on the testing I've done on MF and LF lenses (approaching 100 lenses) and the test reports I've read on 35mm lenses, I think the 1.5 factor you mention is too high for the differences between the formats for ON FILM lens resolution. I've seen some fantastic numbers for the aerial resolution of 35mm lenses, but at this point on the technology curve, the film seems to be a real equalizer. Based on ON FILM testing, the best achievable 35mm resolutions I've seen run about 10 - 20% better than the best MF, which are in turn about 10 - 20% better than the sharpest LF lenses.

> So the MF will generally yield a sharper
> print with better contrast, not to mention smoother due to the film grain
> not being enlarged as much.

Yes, grain size is indeed a factor that can't be overcome no matter how much sharper the smaller format lenses. I shoot Velvia in 4x5 and there is no finer grained color transparency film available in any smaller format (until the new RDP-III comes out this summer, but it will also be available in 4x5 - and 8x10). Of course, there are situations where the grain size is not an issue for various reasons (artistic tastes, small degree of enlargement, etc.), but if what you desire is fine grain and overall sharpeness in moderate to large print sizes, there is just no substitute (at this point in time) for a big piece of film.

Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://www.thalmann.com/

From Contax Mailing List;
Date: Fri, 09 Jun 2000
From: "Bob Shell" [email protected]
Subject: Re: [CONTAX] Tidbits from Contax Days

Medium format lenses always exhibit lower resolution than 35mm lenses because they are designed for a larger usable image circle. They may well resolve as highly as 35mm lenses in the center of the field.

Bob

>To: [email protected]
>Subject: Re: [CONTAX] Tidbits from Contax Days
>Date: Sun, Jun 4, 2000, 8:07 PM
>
> As well, the
>tests on the 645 lenses did seem to indicate they were not quite
>on par with the 35 mm. Perhaps attributable to . . .

From: "Kerry L. Thalmann" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Date: Tue, 11 Jul 2000
Subject: Re: cautions.. Re: Fuji RFs vs. Plaubel Makina

Michael K. Davis wrote:

> If you average the three resoultions
> (center, middle and corner) for the Mamiya 7 80mm f/4 at its best
> aperture, f/5.6, (95, 85, and 60) you'll get an average resolution of 80
> lp/mm.  Doing the same with the Plaubel's Nikkor 80mm f2.8 at either f/8
> or f11 (which had the same results of 85, 76, and 67), we get an average
> resolution of 76 - not nearly as dramatic a difference (80 vs. 76) as seen
> when comparing the center resolutions of these two lenses (95 vs. 85) and
> best of all - the Nikkor's resolution is much flatter from center to
> corner than the Mamiya, which falls to 60 lp/mm at it's best aperture of
> f/5.6 vs. Nikkor's 67 at its best apertures of f/8 and f/11.

Why is it necessarily "better" to have a "flatter" (more consistant) resolution across the frame than to have a higher center and middle resolution, but lower resolution at the corners? I mean afterall, in most of my photographs, the main subject is rarely in the outer most corners of the image. I shoot scenics, so the top two corners are often sky or clouds. If you shoot portraits or still lifes, you probably just have an even toned backdrop in the corners. While I'm a big fan of having sharpness whenever and where ever you can, in many (perhaps most) instances, the actual subject matter in the corners of an actual photograph will be sufficiently lacking in detail to really make a difference. The center 2/3 of the image area, however almost always contains the main subject, so sharpness and fine detail are more critical in these areas. I'm just playing devil's advocate here wondering why you think 85, 76, 67 is better than 95, 85, 60. To me, the latter would seem to indicate a lens that is outstandingly sharp where it matters the most and still decently sharp where it matters less. The former is still very sharp (but slightly less so) where it matters most and a little sharper where it matters less. In any case, just wondering.

BTW, if you want to see some really impressive corner-to-corner resolution numbers, take a look at the 135mm Koni Hexanon at f8 (76, 76, 76). That's the highest corner resolution numbers for any lens we've tested (medium or large format) at any aperture. Not bad for a heavily used 30 year old lens. It also did quite respectable at f11 (76, 76, 67) and pretty decent at f16 (67, 67, 67).

Also, we are discussing rigid bodied cameras here. When using a view camera capable of movements, corner-to-corner sharpness becomes more critical. After all, what is the "corner" when shot straight on may very well end up being the center when making an image where camera movements are employed.

> On that
> note, which lens is more useful at f/11?  The Mamiya, with resolutions of
> 85, 76 and 60 (averaging 73.7) or the Nikkor, with resolutions of 85, 76
> and 67 (averaging 76)?  Which is better at f/16?  The Mamiya, averaging
> 64.7, or the Nikkor, averaging 70?

Well, which is really more useful depends on your application (although I suspect both are quite useful in general). For example, the Mamiya is "best" at f5.6. This will allow the user to use a higher shutter speed (or a slower, finer grained film). This would definitely be more useful to anyone who wanted to use one of these cameras handheld. At f11, it's pretty much a toss-up (the Plaubel is a little beter in the corners where it might not even matter). The Plubel is better at f16, but not as good as either at f11.

> The Nikkor 80mm f/2.8 on the Plaubel Makina 67 is truly SUPERIOR to the
> Mamiya 7 80mm f/4 - the numbers are there - you just have to take it all
> in instead of looking only at center resolutions.  If you consider the
> practical aspect of shooting at smaller stops to achieve DoF, there's no
> question the Nikkor's resolving power is greater where it counts and it
> does so without sacrificing the corners.

Again see my comments above. These are both truly GREAT lenses (and some of the old KO lenses are pretty impressive as well), no disputing that, but to say one is clearly surperior to the other is splitting hairs and reading a bit too much into the numbers (afterall, the sample size for both was one and there are many other factors at work here).

> I still shoot with my Plaubel Makina 67 regularly - carrying it alongside
> my Mamiya 7 II for which I have no intention of purchasing the 80mm until
> my Plaubel dies.  At the moment, with the exception of the rangefinder
> error, the camera is working beautifully, including the meter - which is
> usually the first thing to go.

If the rangefinder isn't working properly, how do you actually obtain maximum sharpness from your Plaubel Makina? As you can see from the test results, small focusing errors can have a very significant impact on sharpness. So, how exactly do you accurately focus your Plaubel? The Koni Omega has removeable backs and a ground glass accessory that can be used for critical focusing instead of the rangefinder, but I know of no such capability for the Plaubel (or Mamiya if it's rangefinder were to go out of adjustment).

> Still, I would have to agree with the consensus that buying a Plaubel
> Makina 67 is a risky venture, but that doesn't diminish the fact that it
> posseses one of the finest lenses ever made.

Yes, but in our tests we were not just testing lenses, but overall system performance. An out of wack rangefinder can negate the advantages of a truly great lens (like the 80mm Nikkor on the Plaubel). That's why it's important to test both the camera and lens in the configuration they will actually be used to make photographs. This is especially true of used rangefinder cameras. Although I would hope Mamiya has top notch quality control to verify the accuracy of the rangefinders on their M7 and M7II cameras, I'd still recommend checking them when new and periodically thereafter. The rangefinder could get misaligned during shipment, thereby not allowing full advantage of the wonderfully sharp lenses.

This whole discussion is a bit academic, unless you make truly huge prints, you are not likely to see with the unaided human eye any difference in sharpness in images made with the M7 and a properly adjusted Plaubel Makina 67. They both certainly have the optics capable of making truly sharp images. At that point, the differences lie in the skill of the photographer and the other links in the photographic and print making process.

Of course, a print from a 4x5 original (or better yet 5x7) shot with a 110mm Schneider Super Symmar XL will blow them both away. And then there's that new 210mm Super Symmar on 8x10... ;^}

Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://www.thalmann.com/

From: "Michael K. Davis" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Date: 12 Jul 2000
Subject: Re: cautions.. Re: Fuji RFs vs. Plaubel Makina

Hi!

Kerry L. Thalmann [email protected] wrote:

: Why is it necessarily "better" to have a "flatter" (more consistant)
: resolution across the frame than to have a higher center and middle
: resolution, but lower resolution at the corners?  I mean afterall, in
: most of my photographs, the main subject is rarely in the outer most
: corners of the image.  I shoot scenics, so the top two corners are often
: sky or clouds.  If you shoot portraits or still lifes, you probably just
: have an even toned backdrop in the corners.  While I'm a big fan of
: having sharpness whenever and where ever you can, in many (perhaps most)
: instances, the actual subject matter in the corners of an actual
: photograph will be sufficiently lacking in detail to really make a
: difference.  The center 2/3 of the image area, however almost always
: contains the main subject, so sharpness and fine detail are more
: critical in these areas.  I'm just playing devil's advocate here
: wondering why you think 85, 76, 67 is better than 95, 85, 60.  To me,
: the latter would seem to indicate a lens that is outstandingly sharp
: where it matters the most and still decently sharp where it matters
: less.  The former is still very sharp (but slightly less so) where it
: matters most and a little sharper where it matters less.  In any case,
: just wondering.

I agree with you completely regarding the top two corners of your scenics, which is what I shoot as well, but disagree with your implication that the lower corners of a scenic "will be sufficiently lacking in detail to really make a difference." I must also stress that it isn't just the most extreme corners of the frame that I'm concerned about. There is quite a bit of real estate residing between the corners and halfway to the center, and it is this area which can be very satisfying as one's eye leaves the main subject and examines minute details in the foreground.

: BTW, if you want to see some really impressive corner-to-corner
: resolution numbers, take a look at the 135mm Koni Hexanon at f8 (76, 76,
: 76). That's the highest corner resolution numbers for any lens we've
: tested (medium or large format) at any aperture.  Not bad for a heavily
: used 30 year old lens.  It also did quite respectable at f11 (76, 76,
: 67) and pretty decent at f16 (67, 67, 67).

Absolutely wonderful numbers, indeed.

: Also, we are discussing rigid bodied cameras here.  When using a view
: camera capable of movements, corner-to-corner sharpness becomes more
: critical.  After all, what is the "corner" when shot straight on may
: very well end up being the center when making an image where camera
: movements are employed.

Agreed, so why sacrifice corner sharpness when the lack of movements is already limiting us in the quest for depth of field. In scenics, it is the corners which typically fall outside the near and far sharps, when we are unable to obtain enough DoF. Again, the bottom corners suffer because more frequently than the top corners because of the greater likelihood of detailed subject there.

: > On that
: > note, which lens is more useful at f/11?  The Mamiya, with resolutions of
: > 85, 76 and 60 (averaging 73.7) or the Nikkor, with resolutions of 85, 76
: > and 67 (averaging 76)?  Which is better at f/16?  The Mamiya, averaging
: > 64.7, or the Nikkor, averaging 70?

: Well, which is really more useful depends on your application (although
: I suspect both are quite useful in general).  For example, the Mamiya is
: "best" at f5.6.  This will allow the user to use a higher shutter speed
: (or a slower, finer grained film).  This would definitely be more useful
: to anyone who wanted to use one of these cameras handheld.  At f11, it's
: pretty much a toss-up (the Plaubel is a little beter in the corners
: where it might not even matter).  The Plubel is better at f16, but not
: as good as either at f11.

Certainly some would prefer a lens that performs best at f/5.6, but without conducting a survey, I'm confident the majority of us are not willing to sacrifice DoF, just to get a wee bit more resolving power. I suspect the majority of your images were taken with apertures at the narrow end of the range, for example. Again, I'll say that the Nikkor's f/11 figures of 85-76-67 vs. the Mamiya's 85-76-60 AND the Nikkor's f/16 figures of 85-67-60 vs. the Mamiya's f/16 figures of 67-67-60 make the Nikkor a superior lens - let me add: for most of us, in terms of resolving power, at least.

: > The Nikkor 80mm f/2.8 on the Plaubel Makina 67 is truly SUPERIOR to the
: > Mamiya 7 80mm f/4 - the numbers are there - you just have to take it all
: > in instead of looking only at center resolutions.  If you consider the
: > practical aspect of shooting at smaller stops to achieve DoF, there's no
: > question the Nikkor's resolving power is greater where it counts and it
: > does so without sacrificing the corners.

: Again see my comments above.  These are both truly GREAT lenses (and
: some of the old KO lenses are pretty impressive as well), no disputing
: that, but to say one is clearly surperior to the other is splitting
: hairs and reading a bit too much into the numbers (afterall, the sample
: size for both was one and there are many other factors at work here).

My whole point was that racing through the table looking only at center resolutions, ignoring middle and center resolutions and failing to compare at which apertures the lenses yield their best performance is an underutilization of the data. I completely agree that it's unfortunate we have only one test sample per lens, but if that's an issue, perhaps we should shutdown the web page. Surely it's of some value for making such comparisons - that's it's purpose after all. And yes, there ARE many other factors to consider besides lens resolution, but again, I was responding to Bob's remarks about the +/- five-inch figures in this table of resolution tests.

: > I still shoot with my Plaubel Makina 67 regularly - carrying it alongside
: > my Mamiya 7 II for which I have no intention of purchasing the 80mm until
: > my Plaubel dies.  At the moment, with the exception of the rangefinder
: > error, the camera is working beautifully, including the meter - which is
: > usually the first thing to go.

: If the rangefinder isn't working properly, how do you actually obtain
: maximum sharpness from your Plaubel Makina?  As you can see from the
: test results, small focusing errors can have a very significant impact
: on sharpness.  So, how exactly do you accurately focus your Plaubel?
: The Koni Omega has removeable backs and a ground glass accessory that
: can be used for critical focusing instead of the rangefinder, but I know
: of no such capability for the Plaubel (or Mamiya if it's rangefinder
: were to go out of adjustment).

I do very little closeup work, with or without the Plaubel. Nearly all my shots include infinity, are shot from a tripod, using small apertures and long exposures. I almost always focus by setting the index mark on the distance scale opposite a value lifted from DoF tables I've calculated myself. These tables yield 1/175-inch diameter CoC's at the Near and Far Sharps in a 10-inch diagonal print (0.0498mm CoC's at the film.) I identified the rangefinder error years ago and have discovered that the amount of compensation I need to give it is linear across the distance scale - I just shift the index mark a tad closer than the hyperfocal distance indicated by my tables. If I do chose to focus with the rangefinder, again, I just back it up a bit. DoF more than offsets any slop I might have here. Fortunately, I never shoot closeups of two-dimensional subjects, wide open.

: > Still, I would have to agree with the consensus that buying a Plaubel
: > Makina 67 is a risky venture, but that doesn't diminish the fact that it
: > posseses one of the finest lenses ever made.

: Yes, but in our tests we were not just testing lenses, but overall
: system performance.  An out of wack rangefinder can negate the
: advantages of a truly great lens (like the 80mm Nikkor on the Plaubel).
: That's why it's important to test both the camera and lens in the
: configuration they will actually be used to make photographs.  This is
: especially true of used rangefinder cameras.  Although I would hope
: Mamiya has top notch quality control to verify the accuracy of the
: rangefinders on their M7 and M7II cameras, I'd still recommend checking
: them when new and periodically thereafter.  The rangefinder could get
: misaligned during shipment, thereby not allowing full advantage of the
: wonderfully sharp lenses.

The misalignment in my rangefinder inhibits the Nikkor optics no more than the errors people can easily make just selecting a plane of focus - even when using SLR's or groundglass. Merklinger encourages us to rack our rollfilm cameras all the way out to infinity for every scenic that includes a distant subject. Surely the impact he's having on foreground detail (an error in judgement, in my opinion) is FAR greater than the errors I suffer with my easily compensated rangefinder malalignment.

: This whole discussion is a bit academic, unless you make truly huge
: prints, you are not likely to see with the unaided human eye any
: difference in sharpness in images made with the M7 and a properly
: adjusted Plaubel Makina 67.  They both certainly have the optics capable
: of making truly sharp images.  At that point, the differences lie in the
: skill of the photographer and the other links in the photographic and
: print making process.

Amen! I rank the factors which can impact image degradation as follows, from most important to least (not a complete list, of course):

Solid camera support and using a shutter speed sufficient to stop subject motion

Avoiding apertures which will make visible the effects of diffraction

Securing sufficient depth of field

Using fine grain film

Using a given lens' aperture of best resolution

Using high resolution film

Using film of high sharpness (as measured by MTF)

This heirarchy mandates my strategy for selecting an aperture:

1) Select your shutter speed - use the slowest speed capable of freezing camera and subject motion. This leaves you with those apertures that can deliver that shutter speed and faster speeds.

2) From this subset of apertures, remove those apertures which would induce visible diffraction. Unlike insufficient depth of field, when diffraction becomes visible, the whole image is degraded.

3) From the remaining subset, select the aperture that will give you ONLY enough depth of field to encompass the near and far sharps of your chosen subject. This leaves you with those apertures which are narrow enough to meet your depth of field needs - without inducing diffraction, but wide enough to offer the shutter speed required.

4) On rare occasions, you'll be left with one or two apertures that may include the aperture of best lens resolution. Shoot at that aperture, if you can do so, without violating the first three rules.

So yes, lens resolution is a relatively small part of the picture (pun intended!)

: Of course, a print from a 4x5 original (or better yet 5x7) shot with a
: 110mm Schneider Super Symmar XL will blow them both away.  And then
: there's that new 210mm Super Symmar on 8x10...  ;^}

Yeah!

Mike
--

From: "Kerry L. Thalmann" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Date: Wed, 12 Jul 2000
Subject: Re: cautions.. Re: Fuji RFs vs. Plaubel Makina

Michael K. Davis wrote:

> I agree with you completely regarding the top two corners of your scenics,
> which is what I shoot as well, but disagree with your implication that the
> lower corners of a scenic "will be sufficiently lacking in detail to
> really make a difference."  I must also stress that it isn't just the most
> extreme corners of the frame that I'm concerned about.  There is quite a
> bit of real estate residing between the corners and halfway to the center,
> and it is this area which can be very satisfying as one's eye leaves
> the main subject and examines minute details in the foreground.

Agreed, but the fall-off in this case isn't that extreme. At f11, the Mamiya lens is 85, 76, 60 and the Plaubel is 85, 76, 67. Assuming the fall-of is linear (it's likely not, but close enough), at the 3/4 point the Mamiya would be 68 lpmm and the Plaubel 71.5 lpmm. Not a huge difference.

> Agreed, so why sacrifice corner sharpness when the lack of movements is
> already limiting us in the quest for depth of field.  In scenics, it is
> the corners which typically fall outside the near and far sharps, when
> we are unable to obtain enough DoF.  Again, the bottom corners suffer
> because more frequently than the top corners because of the greater
> likelihood of detailed subject there.

Sorry, that's a bit of my LF bias showing through. I usually rely on a little tilt to get the foreground sharper rather than relying soley on depth of field. But your point is valid WRT rigid bodied cameras.

> Certainly some would prefer a lens that performs best at f/5.6, but
> without conducting a survey, I'm confident the majority of us are not
> willing to sacrifice DoF, just to get a wee bit more resolving power.

The original poster specifically mentioned photojournalism as the intended application. Hence, my comments about handholding the camera and shooting with a faster shutter speed at f5.6.

> I suspect the majority of your images were taken with apertures at the
> narrow end of the range, for example.

Well, personally, the majority of my images are taken on 4x5, so I usually shoot at f22 plus/minus a stop. When I do shoot medium format, for my application, I tend to be in the f11 - f16 range with an occasional f8. I tend to avoid f22 in medium format because of diffraction, but will shoot at f22 on occasion if I really need the extra depth of field.

> Again, I'll say that the Nikkor's
> f/11 figures of 85-76-67 vs. the Mamiya's 85-76-60 AND the Nikkor's f/16
> figures of 85-67-60 vs. the Mamiya's f/16 figures of 67-67-60 make the
> Nikkor a superior lens - let me add: for most of us, in terms of
> resolving power, at least.

For us landscape types, but I doubt if the majority of MF users are landscape shooters, there are a LOT (almost all, from what I've seen) wedding and portrait shooters who use MF, and the original poster who wants to do photojournalism type work. Different users = different uses.

> My whole point was that racing through the table looking only at center
> resolutions, ignoring middle and center resolutions and failing to
> compare at which apertures the lenses yield their best performance is an
> underutilization of the data.  I completely agree that it's unfortunate
> we have only one test sample per lens, but if that's an issue, perhaps
> we should shutdown the web page.  Surely it's of some value for making
> such comparisons - that's it's purpose after all.  And yes, there ARE many
> other factors to consider besides lens resolution, but again, I was
> responding to Bob's remarks about the +/- five-inch figures in this table
> of resolution tests.

Well, since a LOT of work went into that table, I'm not suggesting throwing it out completely. What I am suggesting is that it just be used as a guideline; a starting point. Just because the ONE Plaubel lens we tested was a little better at some apertures than the ONE Mamiya lens we tested (which was also a little better at some apertures) does not mean every Plaubel lens will be better than every Mamiya lens. What I really encourage is that everyone do their own tests and form their own conclusions based on their particular equipment and how they use it. This is the internet, don't accept anything you read as gospel.

> I do very little closeup work, with or without the Plaubel.  Nearly all my
> shots include infinity, are shot from a tripod, using small apertures and
> long exposures.  I almost always focus by setting the index mark on the
> distance scale opposite a value lifted from DoF tables I've calculated
> myself.  These tables yield 1/175-inch diameter CoC's at the Near and Far
> Sharps in a 10-inch diagonal print (0.0498mm CoC's at the film.)  I
> identified the rangefinder error years ago and have discovered that the
> amount of compensation I need to give it is linear across the distance
> scale - I just shift the index mark a tad closer than the hyperfocal
> distance indicated by my tables.  If I do chose to focus with the
> rangefinder, again, I just back it up a bit.  DoF more than offsets any
> slop I might have here.  Fortunately, I never shoot closeups of
> two-dimensional subjects, wide open.

Fair enough. Still for the original poster shooting photojournalism work (I assume handheld), a bum rangefinder (regardless of brand) might be a big deal.

> The misalignment in my rangefinder inhibits the Nikkor optics no more than
> the errors people can easily make just selecting a plane of focus - even
> when using SLR's or groundglass.  Merklinger encourages us to rack our
> rollfilm cameras all the way out to infinity for every scenic that
> includes a distant subject. Surely the impact he's having on foreground
> detail (an error in judgement, in my opinion) is FAR greater than the
> errors I suffer with my easily compensated rangefinder malalignment.

The problem is unless they test their equipment, most people might never realize their rangefinder is misaligned. Obviously, you've got the situation under control, so this doesn't apply to you. Rangefinders in general tend to be finicky beasts. In a camera that gets bumped about a fair bit (whether during photojournalistic "street" photography, or bouncing around in a backpack on the trail) they need to be preiodically checked and re-adjusted as necessary. That's the one nice thing about a ground glass - once you verify it is properly located, it never needs adjustment.

FWIW, I NEVER just rack focus out to infinity. With a rigid bodied camera, I rely on hyperfocal scales/tables. On a view camera, I use the ground glass to focus, apply camera movements as appropriate, and then since very little of what I shoot in the real word lies in a two dimensional plane, I rely on depth of field for the rest. Since my view camera has a scale on it, I focus on the near and far points, set it to the average of the two and then stop down to the appropriate aperature. This is a slow tedious process, especially if a lot of movements are necessary, but it's the price you pay to shoot large format where nothing is fast (well, except the declining rate of my checking account balance every time I click the shutter).

> Amen!  I rank the factors which can impact image degradation as follows,
> from most important to least (not a complete list, of course):
>
> Solid camera support and using a shutter speed sufficient to stop subject
> motion
>
> Avoiding apertures which will make visible the effects of diffraction
>
> Securing sufficient depth of field
>
> Using fine grain film
>
> Using a given lens' aperture of best resolution
>
> Using high resolution film
>
> Using film of high sharpness (as measured by MTF)
>
> This heirarchy mandates my strategy for selecting an aperture:
>
> 1)  Select your shutter speed - use the slowest speed capable of freezing
> camera and subject motion.  This leaves you with those apertures that can
> deliver that shutter speed and faster speeds.
>
> 2)  From this subset of apertures, remove those apertures which would
> induce visible diffraction.  Unlike insufficient depth of field, when
> diffraction becomes visible, the whole image is degraded.
>
>
> 3)  From the remaining subset, select the aperture that will give you ONLY
> enough depth of field to encompass the near and far sharps of your chosen
> subject.  This leaves you with those apertures which are narrow enough to
> meet your depth of field needs - without inducing diffraction, but wide
> enough to offer the shutter speed required.
>
> 4)  On rare occasions, you'll be left with one or two apertures that may
> include the aperture of best lens resolution.  Shoot at that aperture, if
> you can do so, without violating the first three rules.
>
> So yes, lens resolution is a relatively small part of the picture (pun
> intended!)

And that's only to get the sharpest image on film. To get the sharpest final print involves yet another set of variables (enlarger lens quality, enlarger lens optimum aperture, enlarger vibration, film flatness, enlarger alignment, paper characteristics... or scanner resolution, printer dot pitch...). I do belive in using the best lenses you can afford, but more importntly using them to the best of your ability. Sloppy technique obviously negates any theoretical advantage of a superior lens. Most people would be better of spending money on a good tripod and head and spending the time and money to improve their technique than spending big bucks on the latest wunderlens. Still, as an admitted equipment freak, I'm just as guilty (probably more so) as anyone else in this respect.

> : Of course, a print from a 4x5 original (or better yet 5x7) shot with a
> : 110mm Schneider Super Symmar XL will blow them both away.  And then
> : there's that new 210mm Super Symmar on 8x10...  ;^}
>
> Yeah!

Well, there does get to eventually be a point of diminshing returns. For me, it usually comes down to how much weight am I willing to carry and how much hassle/expense am I willing tolerate to get the results I desire. I've shot with formats up to 11x14, but for now I've decided 5x7 will be my maximum. And, I'm even wondering if that's worth the hassle/expense. 4x5 will continue to be my preffered format, but I may get a 6x12 roll fim back so I don't always have the weight/hassle/expense of sheet film for every single shot. To each his own. Heck, based on what I've read in this forum lately, even the devoted medium format shooters can't seem to agree on which format is best (hint: there is no ONE best format - they all have their advantages and disadvantages - shoot with the one you like and ignore what everyone else has to say on the subject).

Back to the original posters question... The Plaubel is a very compact camera with a GREAT lens. It is, however rather expensive and tends to eventually require very expensive repairs to keep it fully operational (light meter cabling, in particular). The Fuji is a bit more bulky (really a 6x9 body), but moderately priced. It is pretty rugged and reliable, but lacks a built in light meter and is completely manual. The Mamiya 7 is reasonably compact (but not as small as the collapsable Plaubel) and quite light for a 6x7. It also has interchangeable lenses, a built in meter and AE mode. If your budget is really tight. Look into a used Koni Omega. It also lacks a built in meter, and is completely manual (although it does have an impressive series of mechanical interlocks to prevent many common user errors - unintentional double exposure, removing the lens or back without the darkslide in place, taking the picture with the darkslide in place, forgetting to cock the shutter, etc.). It also has the advantage of interchangeable film backs. The Rapid M and Rapid Omega 200 allow changing backs mid roll. The Rapid and Rapid Omega 100 do not allow changing backs mid roll. The camera is rather big and very heavy, but quite rugged. Even though it was discontinued decades ago, it is still possible to get it serviced (recommended), the lenses are excellent and the entire system is quite affordable (the most expensive piece is the rare 135mm f3.5 Hexanon lens at about $500 - $600 - which is till cheap compared to most other medium format lenses for other interchangeable lens 6x7 cameras). A decent body, 90mm lens and roll film back will set you back about $250 (more or less depending on condition). Backs tend to go for $50 - $100, the 58mm lens about $200 - $250, same for the 180. It does not focus close enough for "head shot" protraits with the longer lenses, but should be fine for photojournalism type work. The original poster didn't mention a price range, so I'm not sure if this is applicable. I just wanted to point out that it is possible to give the 6x7 format a try (and even with such niceties as interchangeable lenses and backs) without spending a fortune. On the other hand, if you have the bucks, go for a Plaubel, Fuji or Mamiya 7.

Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://www.thalmann.com/

From: [email protected] (QDurham)
Newsgroups: rec.photo.technique.misc
Date: 13 Jul 2000
Subject: Resolution?

Page 26, this month's Discover magazine: "There are ten billion crystals in a frame of ordinary film -- the equivalent of 20 million digital pixels. (Even today's sharpest digital images have only 2 million pixels.)"

Comments?

Quent

Date: Thu, 13 Jul 2000
From: "Francis A. Miniter" [email protected]
Newsgroups: rec.photo.technique.misc
Subject: Re: Resolution?

I take it that "a frame of ordinary film" refers to the 35 mm format, not to medium or large formats.

But something does not make sense here. If 10B crystals equals 20M pixels, then that is 500 crystals to a pixel. But 500 crystals is going to carry much more information than 1 digital pixel. And the answer cannot be that some of the crystals are not surface crystals, because information contained on subsurface crystals affects the image that can be printed. Besides, that would imply that there are nearly 500 subsurface crystals to 1 surface crystal. This does not compute.

Francis A. Miniter

From: [email protected] (OorQue)
Newsgroups: rec.photo.equipment.large-format
Date: 10 Jul 2000
Subject: Re: LF lenses - MF lenses comparison

>In my opinion, the Super Angulon's sort 
>of performance would disappoint if used 
>directly on medium format, but it would 
>still be usable.

I agree ... I've got a Galvin 2x3, which I find wonderful for toting around the desert, but I lately have come to reflect upon the quality of the results I've been getting from it.

It isn't that the results are poor, they're just not as good as those I get from my Minolta Autocord and/or Bronica SQ-Ai. The shifts and tilts come in useful for some shots but given the caliber of lens that I can afford, it falls somewhat short of being a first-class performer for prints larger than say, 11x11.

In my opinion, using LF lenses on MF film isn't quite the great idea I originally thought it would be. As such, I assume that using a roll-film back on a 4x5 won't work all that much better...

JG

From: [email protected] (OorQue)
Newsgroups: rec.photo.equipment.large-format
Date: 11 Jul 2000
Subject: Re: LF lenses - MF lenses comparison

>Can you cite which lenses you have had >this experience with?

Sure ... I've got two 58mm/f5.6 Grandagons (one with some minor separation, one that is perfect); a 101mm/f4.5 Graflex Optar; a 105mm/f4.5 Tominon and a 210mm/f6.3 D.O. Industries.

I've never run any lens tests on them and I use the Grandagons more often than all of the others combined. All the lenses were purchased relatively cheaply except for the one from D.O. Industries, which came with the camera.

JG

From: [email protected] (OorQue)
Newsgroups: rec.photo.equipment.large-format
Date: 11 Jul 2000
Subject: Re: LF lenses - MF lenses comparison

>Ok, so how did you come to know that 
>these don't compare, resolution wise,
>with your MF lenses?  I'm not doubting 
>you, rather I'm wondering if this holds as
>a firm generalization.

Technically, I don't know that ... however, I have compared photos taken using a 6x6 back on my Galvin and compared them to the images made with my other cameras.

Yes, there are differences in focal lengths to consider but when it comes to capturing fine details -- such as the "fuzz" around a cactus needle or reading the numbers off a license plate annual registration tag that is 30' away -- the Autocord and Bronica do a much better job. The images also tend to "pop" more, suggesting they are higher in contrast as well. One of these days, I will get around to formally testing them but I'm more interested in results than specs...

(Although they measure well, I sometimes wonder if the problem isn't that the Graflex backs do a poor job of keeping the film flat ... however, after shooting a few rolls using a borrowed Horseman back, I didn't notice any significant improvement.)

JG

From: Harald Finster [email protected]
Newsgroups: rec.photo.equipment.large-format
Date: Tue, 11 Jul 2000 Subject: Re: LF lenses - MF lenses comparison

OorQue wrote:

[lens performance LF vs MF]

Probably you can't generalize here. In theory MF lenses should be better than LF lenses due to the larger image circle.

I have personal experience with a Zeiss 110 2.0 compared to the 110 5.6 Super Symmar with landscape images.

I did not carry out any 'formal' comparisons but the 'subjective' result is, that I prefer the Symmar.

Probably landscape photography requires more than pure resolution and contrast - just speculating.

> (Although they measure well, I sometimes wonder if the problem isn't that the
> Graflex backs do a poor job of keeping the film flat ...

Film flatnes seems to be a very important issue when comparing LF to MF: I compared the Super Anguklon 47 XL with a Linhof Back to the Zeiss 50 and the 50 seemed to be much much sharper until I noticed, that the film flatness of the Hassi back is far better than that of the Linhof (6x9) back.

This seems to be the limiting factor especially with very short focal lengths.

Greetings

Harald

Date: Mon, 10 Jul 2000
To: [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: LF lenses - MF lenses comparison

The latest LF lenses are quite surprisingly high resolution compared to many older LF lenses, and some older lenses aren't bad either. Since there is more competition in LF lenses, you can often find them in leaf shutters for less than the same lens and shutter in a medium format camera mount (e.g., Hasselblad archbody roddenstocks vs same roddenstocks in generic lens board mount is circa $1000 US different (about 40% on some optics).

Chris Perez and Kerry Thalmann have tested sundry LF vs MF lenses for resolution, see Chris' COST OF QUALITY analysis on $$ per lpmm LF vs MF at http://www.hevanet.com/cperez/proposal.html - in general, the newer lenses turn in higher resolutions, but at much higher cost per lpmm, the used MF lenses tested were more pricey than the older LF used lenses, and as noted, the medium format lenses, where you have a captive marketplace for any one lens mount, is generally higher cost than more competitive LF market? see also http://www.smu.edu/~rmonagha/mf/mfbest.html

in short, if you have the newer and pricier LF lenses, you probably won't notice much if any resolution loss against shooting 6x7 in a medium format body with a similarly current MF lens. If you have an older LF lens, the new or older MF lenses will probably do as well or better, depending on the lens and its cost.

An intriguing (to me ;-) issue is how much is the cost of extra quality? In other words, the extra resolution of say a 35mm SLR Leicaflex lens by Leica vs. similar focal length/speed 35mm SLR lens by Nikon or Canon - yes, perhaps the Leica lens will deliver 10% more resolution, but the cost is what? - 200% or 300% more for those 10 more lpmm. Obviously, I'm ignoring bokeh and other subjective factors etc. But is going from 80 or 90 lpmm (Nikon..) to 90 to 100 lpmm (Leica..) worth that 2 or 3 times greater cost? Obviously it is to some buyers, but when you figure out the extra enlargeability of having 100 lpmm vs 90 lpmm vs 80 lpmm, it is rarely likely to be visible in prints below 11x14, which are very rarely made. It costs a whole lot more to bring a lens to state of the art, for modest gains, which can make the older lens seems like raving bargains ;-)

If you spend $1000 extra on the higher resolution lens, each of those lpmm are costing you about $100, while the basic Nikon OEM lens (say $1000/80 lpm) is costing you $12.50 per lpmm. YOu are paying twice as much to get a 13% improvement in resolution, but each of those lpmm resolution increases is costing you 800% more than your base rate ($100 vs $12.50). You will have to do a lot of prints beyond 11x14" to justify that expense, IMHO, given that it is only a 13% increase in resolution.

By comparison, shifting to medium format with a larger negative and similar resolution lenses works out to a few hundred percent increase in enlargeability improvements, readily visible accutance and shadow detail etc. effects in even smaller prints, and other factors. Similar points for LF vs MF upgrades too ;-)

I think you can make some similar arguments in Medium format, and by extension here, to the issues of LF vs MF. If your older LF lens is say a 135mm WF ektar ($375 used, 76 lpmm, $4.90 $/lpmm) it may be a heck of a lot better buy than a similar coverage hasselblad optic that costs ten times as much but which can't be used on a LF camera, while the lF optic can be used on LF and with a 6x6cm back (and 6x7..). YOu might not notice the loss of those 4 or 5 lpmm in resolution from the zeiss optics, but you will certainly notice that lighter feeling in your pocketbook ;-)

In my current projects, this is more evident when considering the issue of panoramic backs for 5x7" vs. panoramic camera, or 6x12cm back for low cost 4x5" camera with 90mm LF lens vs. cost of medium format panoramic camera. Here, you are doing the reverse of the poster, namely, trying to put LF format onto rollfilm by taking a panoramic slice 120 rollfilm wide. The more I look at these tradeoffs, the harder it gets to justify a more compact (but not that more compact than a lite field camera 4x5, say) medium format panoramic camera, esp. since the 4x5" adds 4x5 and multi format capabilities, depending on the rollfilm backs chosen (or cut film..)

Chris suggests you figure out what you are paying per Lpmm in $ when comparing two systems, and decide on that basis. I am suggesting that a better parallel approach might be to see how much extra resolution you get, and at what cost per lpmm. This approach highlights how astonishingly good many of the used older cameras and optics really are, and how today's pricier cameras haven't really achieved such great optical improvements (convenience, maybe yes ;-).

Hmmm. I'll have to consider working up a cost of quality improvement page ;-) grins bobm

From: [email protected] (OorQue)
Newsgroups: rec.photo.equipment.medium-format
Date: 06 Jul 2000
Subject: Re: LF real benefits (not resolution, shifts) was Re: 6x6 virtues

>The real benefits of large format are the 
>greater accutance and shadow gradation 
>rather than higher resolution on the larger 
>film area. This is why older lenses, some 
>with rather modest resolution figures, still 
>work well in large format when compared 
>to medium format lenses that provide
>higher onfilm lpmm resolutions.

This is also why using large-format lenses on a medium-format camera isn't perhaps the great idea that I once thought it was.

This past weekend, I went out with both a Galvin 2x3 and my Minolta Autocord. The lens on my Autocord clearly outperformed the 80mm Heliogon lens on my Galvin and while the tilts and shifts came in handy, it would be difficult to argue the Galvin came up with better images despite being able to straighten converging vertical lines.

JG

From: [email protected] (BHilton665)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: why MF produces sharp picture ? just film size?
Date: 12 Aug 2000

>From: [email protected]  (DaveHodge)
>
>The emulsion on films is the same regardless of film size.  Plus-X Pan film
>in 35mm has the same emulsion as Plus-X Pan in 120.

A well-known photographer (Jack Dykinga) once told me that the clear base of 35 mm film was thicker than the base used for MF film and consequently MF would be slightly to moderately less contrasty (depending on the actual film). For example I just pulled the data sheet on a Kodak film and it says 35 mm has a 5-mil acetate base but 120 (MF) has a 3.6-mil acetate base. Which is another (slight?) advantage of 120.

From: [email protected] (MPS)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: why MF produces sharp picture ? just film size?
Date: Sun, 13 Aug 2000

....

I don't know about the conclusions above, but Ilford states in their literature on HP5+ that their 35mm is on 0.125mm acetate base while their 120 and 220 is on 0.110mm acetate base which also has an antihalation backing that clears during development.

It's a total guess on my part, (and likely incorrect), but my assumption is that the film makers make the 35mm thicker due largely to the stress on the sprocket holes. Whether a 1mil thickness difference translates to any perceptible image difference is anybody's guess. All I know is that the thinner, wider 120/220 is much harder to spool onto developing reels.

mps

From: John R Pierce [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: why MF produces sharp picture ? just film size?
Date: Sun, 13 Aug 2000

[email protected] (MPS) wrote:

>to the stress on the sprocket holes. Whether a 1mil thickness
>difference translates to any perceptible image difference is anybody's
>guess. All I know is that the thinner, wider 120/220 is much harder to
>spool onto developing reels.

well, way back when, I used to fool around in a friends darkroom doing various sorta experimental things with him. I recall one set of tests we did with 4x5 tri-X... There were these cool 4x5 filmpacks that held like 8 or 10 sheets of 4x5, you pulled paper strips polaroid style to bring the next sheet to the front... anyways, this stuff was quite a bit thinner base than the standard 4x5 tri-X. We shot a whole pile of tests on both kinds using the same camera, lens, setups... We got consistently better results on very high contrast things (light flares, etc) on the thinner base, we surmised this was due to less scattering in the thinner base. Both films were sufficiently similar in all other characteristics (contrast, grain size, latitude) such that we couldn't otherwise tell them apart.

we both lamented when these nifty film packs ceased to be regularly available circa 1980. I had a lot of fun with a borrowed Crown Graphic armed with a Super-Angulon 90mm and those film packs.

-jrp

From: [email protected] (Jess4203)
Newsgroups: rec.photo.equipment.large-format
Date: 10 Jan 2001
Subject: Re: LF lens on MF cameras (specifically Mamiya SLR)

Wayne:

Just a few comments on your comments. Yes, the resolution numbers I'm quoting for LF are for f22, but the best resolution for almost all LF lenses is at f22.

true, the edge resolution numbers are not strictly relevant in MF as you aren't using the edges of the field, but there will be some falloff towards these numbers at the edges of the MF field. As you note, resolution in the aerial image is much greater than on the film. While some have complained that the relation 1/Rtot= 1/Rfilm+ 1/R lens is not strictly true, it does give some indication of why your numbers are so high compared to the ones I quote. What you have left out is that the resolution of MF lenses is also going to be much greater in the aerial image. You also may be missing the astigmatism if you are focusing on one set of lines (verticals) at a time and then refocusing on the horizontals by moving the loupe.

As far as the film flatness issue, I think if you compute the depth of focus at f22, you will see that film bowing in the holder is not going to be that much of a factor. How much does the film bow when the camera is horizontal? A sixteenth of an inch? (Less, I'd say.) I believe depth of focus is greater than even that. Besides, can you really swear that roll film is flatter? What about the whole "reverse curl" issue for some film magazines (I think Hassie and Rollie have reverse curl).

I will restate: LF lenses have less resolution than MF lenses, so better results will be obtained using MF lenses on MF than adapting LF lenses to the format. This is a design problem because of the wider field that LF lenses have to cover. LF lenses on LF will probably still beat the best of the MF lenses on MF, however.

Regards,
Roy

From Contax Mailing List;
Date: Thu, 5 Apr 2001
From: [email protected]
Subject: Re: [CONTAX] Med Formt

Hi Ben,

MF's larger size really is responsible for the greater smoothness of tone and gradations that you've seen! I attended an exhibit of original Ansel Adams prints a few weeks ago. Naturally they were stunning; most were from 8x10 originals. There was an enormous print at the entrance, which I'd guess was at least 30x40...on close inspection, it was less sharp than a 16x20 version also on exhibit. Still beautiful, but even an 8x10 original negative will start to degrade if you print it big enough. Of course it was shot on the film of 60 years ago, so I can only imagine what it might look like if Ansel had today's emulsions available.

Here are some links to get you going with LF info. These are probably the best two sources around...you'll find enough reading material here to keep you busy for weeks!

http://greenspun.com/bboard/q-and-a.tcl?topic=Large%20format%20photography

http://www.ai.sri.com/~luong/photography/lf/

The first is what you might call a spin-off from photo.net, devoted to Q&A about all aspects of LF photography. The second is an excellent collection of articles, how-to's, reviews, data sheets, and so on. Have fun wading through them! Ha ha, it's such fun being a bad influence ;)

If you have the urge to get a book on LF, a good starter guide is one written by Steve Simmons, who publishes "View Camera" magazine. I *think* the title is "Using the View Camera", although I don't have it in front of me right now.

Very best,
Danny

From: [email protected] (brian)
Newsgroups: rec.photo.equipment.35mm
Date: 9 Jun 2001
Subject: Re: 35mm equal to larger format?

I think the article you are looking for can be found on this page:

http://www.photodo.com/nav/artindex.html

Look for the one comparing 35mm, MF and LF. Its a good article and pretty solid in terms of information, but a comparison of actual photographs would be better. I've worked in all formats up to 11x14, and I know that small formats can be very good if you do everything right, but there is still a feeling in large format contact prints that is hard/impossible to duplicate. I could always tell the difference between 11x14 contact prints and 11x14 enlargements from 4x5 negatives, although the difference is subtle.

Brian

Date: Tue, 23 Oct 2001 
From: "Eugene A. Pallat" [email protected]>
To: [email protected]
Subject: Re: [HUG] Grain and Print size- a bit long

Mark Rabiner wrote:

> "Eugene A. Pallat" wrote:
> > At lot also depends upon which film was used.  Pan-F or Technical pan vs. Tri-X.  The choice of developer is also a factor.
> And viewing distance.
> And if you use a Loup or not.

Interesting that you mentioned viewing distance.  That's an important factor in forensic photography.  According to the American Opthalmic Association, the average viewing distance for pictures, books, etc. is 15 inches.  Therefore,
the print size is a function of the focal length of the lens and the size of the negative.

The formula is to divide the viewing distance by the focal length of the lens.  This gives the degree of magnification required.  Then multiply by the negative size, and that's the required size of the print.

M = 15 / F

M  = magnification
15 = viewing distance (381 mm)
F  = focal length

W = N * M

W = width (and height) of print
N = size of negative
M = magnification from above

If you use mm for lens FL and negative size, use 381mm.

All of my Blad backs make an actual negative size of 55mm square.  The following show required print sizes for various Zeiss lenses on the Blad.  I use 38, 50, 80, 120, and 150mm.  The table is more extensive.

   FL      mag.       width           height
 38 10.03 21.71 x 21.71
 40  9.53 20.63 x 20.63
 50  7.62 16.50 x 16.50
 60  6.35 13.75 x 13.75
 75  5.08 11.00 x 11.00
 80  4.76 10.31 x 10.31
100  3.81  8.25 x  8.25
105  3.63  7.86 x  7.86
110  3.46  7.50 x  7.50
120  3.18  6.88 x  6.88
135  2.82  6.11 x  6.11
150  2.54  5.50 x  5.50

These are some numbers for a 35mm where the negative area is 24x36mm.

FL      mag.      height           width
15 25.40 24.00 x 36.00
16 23.81 22.50 x 33.75
20 19.05 18.00 x 27.00
24 15.88 15.00 x 22.50
28 13.61 12.86 x 19.29
35 10.89 10.29 x 15.43
50  7.62  7.20 x 10.80
55  6.93  6.55 x  9.82

These dimensions can be adjusted slightly for available paper sizes.

A late friend, who also did forensic photography, and I were board members on the Society of Photographic and Scientific Engineers in Cleveland, Ohio.  He usually used a 3 inch lens on his 4x5 which required a 20x24 print.  That way
he could charge more money.

There was one case where he measured the distance from the jury box to the opposite wall and made the print size to correspond.  The lawyer opened the print, like a book, when items on the photo were discussed by witnesses.  The
other side settled quickly, because they said every time that print was opened, they saw their losses increasing.

Gene Pallat



Date: Tue, 23 Oct 2001 
From: Michael Vanecek [email protected]>
To: [email protected]
Subject: Re: [HUG] a Hasselblad conscience

Oops - this went to a person instead of the list - let's try this again...

For a period of time, I did the Orley's Lowriding centerfolds and covers
using Hasselblad - they required medium format. But the filler photos
were done using 35mm. It really depends on the requirements of the
publisher. Most smaller images, action shots and the like are probably
35mm. Full-page images, covers and centerfolds, depending on the
magazine, are most likely done with medium format - though 35mm is not
out of the question. It's not a matter of superiority - it's a matter of
the right tool for the job. If you ever watch NG shows or look at the
front or back of the magazine with info about the authors of the
particular segments, you'll find each one will have their own preference
in equipment from 35mm, 2.25", 4x5", but 35mm predominates. Naturally,
the assignment also dictates to some extent the equipment used. For the
zooms required in nature shots and the travel to get to the locations,
or the anonymous street photography, 35mm can't be beat. Most
journalists seem to prefer 35mm - it's light and unobtrusive. You'll
even find a mix of 35mm and 645 used in magazines sporting swimsuit
editions. Watch shows about photographers examining the slides on the
light-table, and you'll notice a mix of 35mm and medium-format slides.
It can't hurt to have a professional collection of both 35mm and 2.25"
equipment if you're interested in doing magazine photography. Don't
insist on using the Hassy just because it's "superior". Use it because
it's appropriate and because the client needs that format. Vice versa -
if the client requires 35mm, then you're in business if you can provide
that service. These guys are aware of the limitations of format and
their requirements, so don't second-guess them. I prefer to use the
Hassy for most of what I do, but if the client needs, or if the
situation calls for 35mm, then I'm up to that too. It's money in the
pocket and perhaps another Hassy lense...

Mike

Matthew Midnight Gaylen wrote:

 > Speaking of he superiority of Hasselblad equipment, is it true that 
most magazine (sports illustarted, national geographic etc... 
photographers use 35mm format cameras?
 >
 >


-- 
http://dotfile.net/ - Dedicated to Open Source Software

To: [email protected]
Date: Tue, 23 Oct 2001 
Subject: Re: [HUG] a Hasselblad conscience
From: Evan J Dong [email protected]>

I work in the publishing world and i can tell you what type of images
comes through the majority of general publications.

For a high quality magazine and most other general main stream news
weeklies that requires detail oriented images,  majority of supplied
images are shot on medium format transparency film. 

I had seen film in sizes ranging from 6.45,6 x 6, 6 X 7, panoramic 6 X 12
to 6X 17. 4 X 5, 5 X 7, and occasionally 8 X 10.  

There are some photographers who wants to go digital and they usually
supplied their own digital SCANNED images that are color corrected and
edited to the publishers. 

Now, that is not to say that 35mm has no place. Depending the magazine or
publisher, majority of images are 35mm chromes or digital images prep by
the photographers. 


On occasion, I meet up with these photographers and do see their
equipment. Your standard Leica, Canon, Nikon, Contax, Pentax and Minolta
35mm.
Medium format consists of Mamiya 6.45 & 6 X 7, Hasselblad, Fuji, Pentax
and Bronica. 4 X 5 = Sinar , Horseman and Calumet.  SO there is a wide
gamut of equipment used.  The rush is on to supplied scanned digital
images with some digital camera materials. The digital camera shots are
being used more frequently in place of the 35mm where detail is not as
important. 


Evan


Matthew Midnight Gaylen
[email protected]> writes:
> Speaking of he superiority of Hasselblad equipment, is it true that 
> most magazine (sports illustarted, national geographic etc... 
> photographers use 35mm format cameras?
>  
> -- 
> Prints, The Artist Formerly Known as Midnight


From: "Charlie Goodwin" [email protected]>
To: [email protected]>
Subject: Re: [HUG] Grain etc.
Date: Wed, 24 Oct 2001 

Oliver,

Exactly...for critical application, use the depth of field scales
conservatively, and for very critical applications, use them very
conservativly.   Critical being equivalent to great enlargement and close
viewing distance combined, i.e. essentially the "perceived" size of the
image; the angle of view the image subtends for the viewer.   If the image
takes up a 90 degree portion of the viewer's field of vision, that's pretty
big, and will need to be very sharp to maintain the illusion of critical
sharpness.   If the viewer moves closer so the image encompasses 140
degrees, he/she is in super close and the sharpness is more critical yet.
It doesn't matter whether the image is 8 inches or 8 feet, or whether the
eye is near or far, but the "combination" will or won't reveal the level of
unsharpness.

All the above is influenced by external factors... print sharpness, camera
unsteadiness, the slight imperfections of the optics, multiple filters in
the optical path, the acuity of vision of the viewer, even the more
agressively textured print surfaces...almost endless factors that muddy the
mathematical simplicity of the depth of field scales.

Previous posts correctly mention viewing distance...presuming a given image
size...but for a more general formulation, in essence, it's how "closely" an
image will be examined-the relationship of the eye to a given detail, that
determines how fuzzily that detail may be allowed to be rendered.

Charlie



> Just to add my 2 cents worth, I understand that DoF Scales are also based
> upon assumptions about the acceptable Circle of Confusion (CoC) which is
> important in planning enlargements. While I cannot recall the published
> source, I do remember that for greater sharpness, one should use the DoF
> scale as if (repeat, as if) one were shooting at one stop wider open than
> the f-stop actually set on the lens, e.g., with the lens at f/16 use the
DoF
> scale as if the lens were set at f/11.
>
> Oliver


From: "nathantw" [email protected]>
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Hassey 150 vs Nikon 105 2.5
Date: Thu, 27 Dec 2001 

Hi,
I did a test a few years ago with my Hassy 120mm Makro Planer (CF) and a
85mm f/1.8 AF Nikkor with appropriate lens hoods. I went to my rooftop and
shot identical pictures with the same type of film (Kodak 100S slide film)
with both cameras on a tripod. I tried both lenses at each aperture to makes
sure I got the "sweet spot" for each lens. REMEMBER all you sticklers for
scientific accuracy, this was for my purposes and only my purposes. So my
findings are my findings and doesn't take into account wind accuracy, sun
spots, film plane deviations, dust on the lens, or the fact that I'm
comparing apples with oranges. However, just so you don't need to ask, I
used a Nikon N8008 and a Hasselblad 555elx with a A12 back. Both used a
Gitzo 224 tripod. I used a Gossen Luna Pro F for exposures.

My findings were rather surprising. In theory medium format lenses are
suppose to be less sharp than than a comparable 35mm lens. What I found was
that the Hassy lens was as sharp as the 35mm lens at its best apertures.
This was a tad surprising to me because the 120mm Hassy lens isn't suppose
to be a good performer set at infinity. Since I used Nikon lenses almost
exclusively up to that point I was very pleased to find that the sharpness
was so high. I was able to pick out individual bricks on buildings over a
mile away with both lenses. However, I did find a difference between the
two. The difference, other than operational, was the fact that the Hassy
lens had LESS contrast than the Nikon lens. I actually LIKED the lower
contrast because it allowed me to get more details in shadows. In comparison
the Nikon lens had really high contrast. Details in shadows weren't as
apparent in those slides.

To answer your question, the Hassy had a different look than the Nikon. I
can't say either one blew away either. I actually liked the Hassy look more
than the Nikon because of the lower contrast. I would look very highly at a
Contax 35mm camera because of the Zeiss lenses if I wasn't so heavily
invested in Nikon. On the other hand I'm perfectly happy with the photos I
get with my Nikon. I like the consistent "warm" color rendition that Nikon
lenses all have. I know what to expect from them. So which one should you
get? Beats me. As I mentioned above, it's comparing apples with oranges.

Oh, to let you know, I shot a photo with a chrome 150mm Hassy lens when I
was in Cub flying over San Francisco. I shot a heavily backlighted scene
with the sun reflecting off the ocean. The picture showed NO FLARE
whatsoever. Again, it displayed shadow detail I wouldn't have gotten with a
Nikon.

Nathan


"J. Boyer" [email protected]> wrote 
> Hello everyone,
>
> I am interested in purchasing a lens for portraiture.  I have my eye on
> either a used Hasselblad 150 F4 or a Nikon 105 F2.5.  I have bodies for
> both.  Does the Hasselblad simply blow the Nikon away?  I would probably not
> enlarge beyond 11X14 and mostly be at 8X10".  This would not be for
> professional work, but to expand my capabilities in this fascinating hobby.
> The price differential is quite high.  The Hassey lens I have seen is a CT*
> lens and the price is $1000; the Nikon, on the other hand can probably be
> had for around $200 dollars.  I would also be interested in opinions about
> the non T* chrome 150 Hasselblad lens.  They are going for about $600-$700
> bucks on ebay and more reasonable.


From nikon mailing list:
From: "Elizabeth Vegvary" [email protected]
Subject: Re: [Nikon] Re: medium format v 35mm (was: OT is this sound advice?)
Date: Wed, 29 Aug 2001 

> This debate is relevant to the original questioner, who had been
> advised not to use 35mm for portrait photography.  What have others
> who have used both 35mm and medium format found?

Props to Mr. Owlett for his gracious replies.

I shoot both 35mm and medium format and I have to say, that hands down, for
the color print work I do - weddings, portraits, maternity - 35mm can't come
even close to the quality I get with medium format. My black-and-white
available light candid photographs can really go either way - but in those
cases I'm shooting expressely for a grainy look and the enlargements are
very rarely over a 5x7 size.


I took a seminar from John Woodward once and he had this amazing theory on
the quality issue - he refers to it as "the black factor." I'll cut and
paste some of his words - don't tell any copyright lawyers, though...okay?
;-)

"Quality in any photograph is directly related to the size
of the image area being used. There is no point using an 8 by 10
view camera and then cropping the negative down to
35mm, and expecting the best possible quality.
It is important to understand that grain is the name
given to the silver particles implanted in the films
emulsion. If you can envision the grain as dinner
plates sitting on the top of your table, you have a pretty
good idea of the structure of the image receiving
material within film. Instead of light hitting the grain,
lets envision food falling from the sky onto the dinner
table. Only the food landing on the dinner plates will be
usable. The rest of the food will fall on the tablecloth,
chairs, seats and the floor.

The area outside of the grain, has no ability to capture an image.
For this reason that area outside of the grain remains
clear on negative film, and [unexposed]
black, on transparency film. When you print an image
from a transparency or negative, this black area is
seen on the final print and certainly is the key factor in
quality and color saturation. You see, The more
black factor you have in the image, the more muted
your colors will become.

To visualize how affects final quality,
shoot identical scenes on 35mm and 6 by 7 negatives.
To complete this test, lay an 8 by 10 enlargement from
35mm next to an 8 by 10 enlargement from a six by
seven negative.

If you overlap to areas of continuous tone [such as the
sky] you will see the effect I am describing.
Any light hitting an area of film which has no grain,
is not captured. the more you
enlarge your image source, the more you are
enlarging the black factor as I call it."

I strongly endorse medium format equipment for folks who are shooting images
which are to be purchased by clients. My Hasselblads don't compete with my
F100 - they really complement one another, but I will admit up front that my
format of choice in most situations is medium.

But what do I know? I mean, Joyce Tenneson supposedly shoots her beyond the
beyond images with Canon gear!


Elizabeth



From Contax mailing List:
To: [email protected]
Subject: Re: [Contax] Re: 35mm lenses on 645
Date: Mon, 4 Mar 2002

Many list members are probably already familiar with the Photodo website.
Most of us look at that site for the lens information but there are some
interesting articles there also.  One of these articles, " 35 mm, medium
format, or large format?" indirectly addresses this current 35 vs MF lens
discussion.  Zeiss 35 and MF lenses are used in the experiments that were
done.

http://www.photodo.com/nav/artindex.html

Jason





Date: Mon, 4 Mar 2002 
From: Bernard Cousineau [email protected]
Subject: Re: [Contax] 35mm -vs- 645 resolution
To: [email protected]

> Resolving power is the ability to reproduce detail to a certain degree.
> The contention is 35mm glass has a better resolution because of the ratio
> between the size of the lens and the negative size, as compared to that of
> 645 glass.

I think that this is simply an observation that was true many years ago but no
longer applies. When 35mm first became popular, the average medium format
camera had a very simple lens, often just a triplet or even a single element
(i.e.: Kodak Brownie). The better medium format cameras had Zeiss Tessars (4
elements). These cameras were meant to produce contact prints (typically of 6x9
cm size).

Lenses for 35mm were designed from the start for enlargements, so they needed
to be much better. The original Zeiss Sonnar 1.5/50 of 1932 is still considered
to be one of the finest optics ever made, and its design required huge effort.
I have read at least one author (can't remember which) who claimed that this
specific lens design represented one of the great mathematical achievements of
the period between the two world wars.

If we look at current Zeiss lenses, the resolution advantage of 35mm lenses has
disappeared. Lenses such as the Makro Planar 4.0/120 for Contax 645 or the
better Hasselblad lenses (Biogon 38, Distagon 60, Planar 100, Sonnar 180,
Superachromat 250) are every bit as good as, or perhaps even better than the
best 35mm lenses (which are also made by Zeiss, as we all know :)

The factors that limit the ability of a lens to resolve fine detail are the
qualities of the lens design, the ability to manufacture and assemble lens
elements to extremely fine tolerances, and the inescapable optical law of
diffraction. The image format really does not come into play until you reach
the fourth factor: cost. If cost is not a critical factor (as is the case for
spy satellites that you mentioned), huge lenses can be made that are
diffraction limited. One of the issues of "Innovations" (published by Zeiss)
explains how a limiting factor for telescope optics is making large optical
elements (mirrors in this case) that won't distort under their own mass.

Bernard



From rollei mailing list:
Date: Fri, 02 Aug 2002 
From: Bob Shell [email protected]
Subject: Re: [Rollei] Medium Format lenses on 35mm?

Brian O'Connor at [email protected] wrote:
> Can medium format lenses, built to a lower expectation of enlargement really
> cut it on
> 35mm?

Yes.  It depends on the specific lens, of course, but when you put one on a
35mm camera you are only using the central part of the image it projects,
and that is almost always the best part.

Bob


From: g*[email protected] (Gregory W Blank)
Newsgroups: rec.photo.equipment.large-format
Subject: Re: How good are large format lenses for medium format?
Date: Sun, 03 Nov 2002 

Without any science for documentation,...I'll state this,.... having 1/3
stop or smaller
adjustment ability is a big, big plus when exposing film,....that in
itself is a major plus
for LF Cameras verses some medium format/& of course LF has movements.
Regardless of lens resolution issues DOF
in medium format seldom looks good enough to my eye & f/22 for a 6x6 cm
negative or slide & I frequently find myself
doing out door images for publication where f/22 is not small enough to
get accurate exposure,Lots of times where my base
exposure would be better starting at f/22.5 for a full stop bracket. The
minimum is f/22 on my Bronica 40mm PS lens,PS lenses
are said to be rather sharp according to photographers I have spoken with
in the past.

To me f/22 is barely stopped down enough for wide angle depth of field,
under my use. I believe f/22 is inadequate
for the dimensional size of the frame 6x6cm which is half as big - or +of
the 4x5. 6x6 is about 1.75X  bigger than 35mm
Granted there are no movements on a Bronica but I think 35mm lenses are
relatively
sharper than medium format,...of course this is just a personal
observation. The only advantange
is the larger negative size from 35 to 6x6. It would be interesting to
take a relative image and compare them I
think I'll try it.

Leonard Evans [email protected] wrote:

> I just used my new Fuji 300 mm lens to experiment with a "self
> portrait".  Since I couldn't be sure of the focus I got a good ways
> back, about 11 feet.  As a result I cropped the 4 x 5 negative to a
> little over half size.  I was surprised by the high quality of the image
> but I didn't make any systematic comparisons with any medium format lenses.
>
> Generally, how do good quality lenses designed for 4 x 5 with movements
> compare to comparable focal length medium format lenses of average quality?

--
Photographic website @
http://members.bellatlantic.net/~gblank


From: [email protected] (TDuffy8486)
Newsgroups: rec.photo.equipment.large-format
Date: 04 Nov 2002
Subject: Re: How good are large format lenses for medium format?



Leonard wrote:
>I just used my new Fuji 300 mm lens to experiment with a "self
>portrait".  Since I couldn't be sure of the focus I got a good ways
>back, about 11 feet.  As a result I cropped the 4 x 5 negative to a
>little over half size.  I was surprised by the high quality of the image
>but I didn't make any systematic comparisons with any medium format lenses.
>
>Generally, how do good quality lenses designed for 4 x 5 with movements
>compare to comparable focal length medium format lenses of average quality?
>--
>Leonard Evens      [email protected] 

Leonard,

I'm certainly no expert, but I've seen resolution published for my favorite
large format lens, the apo-symar 210 mm, of about 68 lines per mm at its
optimum fstop.

When Pop Photo tested the Zeiss lenses for the Contax 645 the center resolution
topped out at about 80 lines per mm.

I don't know if this is an apples to apples comparison, but your experience
mirrors mine. when cropping 4x5 for a more suitable head shot, I've been very
impressed by the final 8x10 print.

Take care,
Tom Duffy


From: [email protected] (Dan Fromm)
Newsgroups: rec.photo.equipment.large-format
Subject: Re: How good are large format lenses for medium format?
Date: 4 Nov 2002


Leonard Evens [email protected] wrote 
> I just used my new Fuji 300 mm lens to experiment with a "self
> portrait".  Since I couldn't be sure of the focus I got a good ways
> back, about 11 feet.  As a result I cropped the 4 x 5 negative to a
> little over half size.  I was surprised by the high quality of the image
> but I didn't make any systematic comparisons with any medium format lenses.
>
> Generally, how do good quality lenses designed for 4 x 5 with movements
> compare to comparable focal length medium format lenses of average quality?

Leonard, I shoot a 160/5.6 Pro Raptar and a 210/9 Konica Hexanon GRII
on 2.25 x 3.25, which is sort of the upper limit of medium format.
They're both great, the Pro Raptar is every bit as good as my 101/4.5
Ektar.

I've shot the GRII against a 200/4 MicroNikkor AIS on 135, it beats
the MicroNikkor at 1:2 @f/11 and f/16, ties it @ f/8.

I also shoot a 38/4.5 Biogon on 2x3 (doesn't cover).  Its greater than
the other lenses I use on 2x3, but then its an exceptional optic even
for 2.25 x 2.25.

Cheers,

Dan



From: Bob Salomon [email protected]
Newsgroups: rec.photo.equipment.large-format
Subject: Re: How good are large format lenses for medium format?
Date: Mon, 04 Nov 2002


> Leonard Evens [email protected] wrote
> > I just used my new Fuji 300 mm lens to experiment with a "self
> > portrait".  Since I couldn't be sure of the focus I got a good ways
> > back, about 11 feet.  As a result I cropped the 4 x 5 negative to a
> > little over half size.  I was surprised by the high quality of the image
> > but I didn't make any systematic comparisons with any medium format lenses.
> >
> > Generally, how do good quality lenses designed for 4 x 5 with movements
> > compare to comparable focal length medium format lenses of average quality?
>
> Leonard, I shoot a 160/5.6 Pro Raptar and a 210/9 Konica Hexanon GRII
> on 2.25 x 3.25, which is sort of the upper limit of medium format.
> They're both great, the Pro Raptar is every bit as good as my 101/4.5
> Ektar.
>
> I've shot the GRII against a 200/4 MicroNikkor AIS on 135, it beats
> the MicroNikkor at 1:2 @f/11 and f/16, ties it @ f/8.
> I also shoot a 38/4.5 Biogon on 2x3 (doesn't cover).  Its greater than
> the other lenses I use on 2x3, but then its an exceptional optic even
> for 2.25 x 2.25.
>
> Cheers,
>
> Dan

It isn't current but the German magazine Color Foto in an article in the
3/92 issue did a test of all MF cameras available then and a Linhof
Super Technika V, 23b with a Rodenstock Grandagon 65mm 4.0, a 100mm
Sironar n and a 180mm Sironar N.

They rated Sharpness and edge and center and contrast at edge and
center, both at wide open and f11 and vignetting. They tested head to
head vs the Fuji 680. Also in the test are mamiya Sekor C, Z lenses,
Pentax SMC, Bronica Zenzanon PG, Zeiss Distagon for Hasselblad and
Rollei (6000 as well as SL66), Mamiya G, Schneider for Exacta and Rollei
6000.

If you can not find the copy of the magazine and are interested in the
results (it is in German but the charts are easily understood) we can
mail a set of copies to anyone in the U.S. who wants to see it.

Oh yes - the winners were the Rodenstock view camera lenses.

--
HP Marketing Corp. www.hpmarketingcorp.com Ansmann, Braun, Combina,
DF, Ergorest, Gepe, Gepe-Pro, Giottos, Heliopan, Kaiser, Kopho, Linhof,
Novoflex, Rimowa, Rodenstock, Sirostar, Tetenal ink Jet and cloths,
VR Frames, Vue-All archival products, Wista, ZTS


Date: Mon, 04 Nov 2002
From: "Christoper M Perez" [email protected]
Newsgroups: rec.photo.equipment.large-format
Subject: Re: How good are large format lenses for medium format?



Hello Leonard,

If you use your LF 300mm at f/16 or f/22 and attempt to compare the final
result with a MF lens of the same focal length, I seriously doubt you'd be
able to tell the difference between them.

As others have pointed out, lens designs tend not to be the limiting factors
to pleasing final image resolution.  Film resolution, film plane accuracy,
scene contrast, film developer, and mirror slap (in the case of MF SLRs)
play a large role.

If one is truely neurotic about such things, here are a few things that
Kerry and I have seen 'in general' regarding MF vs LF lenses:

1) LF lenses are quite outstanding and tend to match or better MF optics at
f/16 and f/22.  This is an amazing achievement considering that many LF
lenses have enormous image coverage when compared against MF optics.


2) Shorter focal length LF optics tend to 'optimize' their resolutions for
wider apertures than their longer bretheren.  For instance, 75mm 105 degree
lenses appear to perform optimally at f/11, where 90mm 105 degree optics
seem to be optimized for f/16 or f/22.  Some 300mm lenses seem to do
particularly well at f/22 or f/32.

3) MF lens designers appear to optimize their optics for f/8 or f/11 (again,
depending upon the focal length of the lens).  Some MF designs will even try
to hold as much resolution as they can from f/2.8 on down.  Zeiss designs
come to mind, though Japanese optics appear to have caught up and surpassed
Zeiss in this area over the past decade or two.

I hope this helps.

Regards - Chris



From: "Wes J" [email protected]
Newsgroups: rec.photo.equipment.35mm
Subject: Re: 35mm lenses are always better than MF lenses
Date: Sat, 11 Jan 2003 

Several years ago, the much maligned magazine Popular Photography addressed
this issue comparing 35mm and MF Zeiss lenses.  Their conclusion was there
was more resolving power in the smaller format, but image quality was still
much better with the medium format.

"Elie A Shammas" [email protected] wrote...
> This came to my attention after doing some research on using a MF lens on
> 35mm camera. In particular I wanted to use a Carl Zeiss Pentacon on a 35mm
> Contax body.
>
> Looking at two comparables lenses, for example the 80mm in MF and 50mm
> in 35mm. Since MF project the image on bigger area of film, the MF lens
> manufacturers can afford to have more aberrations in the lens design and
> yet get better results on the bigger film. Hence when MF lens is used on
> 35mm film, one shouldn't expect better quality than a 35mm lens.
>
> So even though MF lenses are or could afford to be technically inferior
> to 35mm lenses, yet they could produce better images in bigger film. This
> inferiority is clear when MF lens is used with smaller film.
>
> I would like to know what you think about this.


From: Michael Benveniste [email protected]
Newsgroups: rec.photo.equipment.35mm
Subject: Re: 35mm lenses are always better than MF lenses
Date: Tue, 14 Jan 2003

 Don Stauffer [email protected] wrote:

>In fact, one does not even need to redesign a lens for a new format. One
>merely scales the dimensions of it. If a 35mm lens design exists that
>works, designer does NOT need to do optical redesign, he merely scales
>by ratio of format dimensions.

This is true of optical design, but a lens is a physical object.
While you could redesign an entire lens in such a manner, there are
good reasons why you would not want to.  The most basic of these is
that the volume of an object, and therefore its weight, increases with
the cube of the size increase.

To use this method to redesign a lens with a 43mm circle of coverage
(35mm) to one with a 75mm circle of coverage (6 x 4.5) requires each
lens element to cover almost twice the area and weight 5.3 times as
much.  To cover 6x7 (92 mm circle), you'd end up with a lens element
that weighs nearly 10 times as much as its 35mm counterpart.

If you merely scaled all components, the medium format equivalent of a
28-70 f/2.8 zoom would end up weighing 12-18 pounds or so.

Looking at real "normal lenses" at the same f-stop, we don't see
nearly the same weight gain, so perhaps real world designers are a
little more sophisticated.

     35mm:  45mm f/2.8 @ 4.1  ounces (Nikon)
 6x4.5:  75mm f/2.8 @ 7.6  ounces (Pentax)
      6x7:  90mm f/2.8 @ 17.1 ounces (Pentax)

--
Michael Benveniste -- [email protected]


From: Tim Daneliuk [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: 50/6.3 for Mamiya vs a modern 20 mm
Date: 27 Jun 2003

Skatto wrote:
> Tim Daneliuk [email protected] wrote:
>
>>Skatto wrote:
>>>Hello,
>>>I'd like to know if the 50/6.3 for Mamiya press at its best f-stop is
>>>sharper than a modern 20 mm for 135mm (e.g. Nikon) at its best f-stop
>>>[...]
>>[...]
>>However, as a practical matter, I would expect that
>>the Mamiya would deliver _better_ final prints than the Nikon, even
>>if the 20mm is "sharper" (and it probably is). [...]

One other point: The smaller the negative format, the MORE resolving
power the lens must have to produce a given size print. Let's
say you want to make an 8"x10" photo which has 8 lpm (line pair per
millimeter - a measure of resolution) - this is probably a reasonable
amount of resolution in a final print of this size.

To make that print from 35mm, you need roughly 8x magnification. For
6x9cm negatives, you need roughly 3x magnification.

Now, the resolution in the final print is the resolution of the negative
_divided_ by the magnification used (assuming perfect enlarger optics
and no other degradation in the enlarging process).

So... to get 8 lpm from 35mm in this case, you will need about 64 lpm
of resolution in the lens/film combo. But for 6x9cm, you will only
need 24 lpm in the lens/film combo. For all practical purposes,
in these resolution ranges, we can assume the film is of no real
consquence and that our resolution is limited only by the _lens_.

IOW, larger format lenses generally have LOWER resolution than smaller
format lenses - it would be too expensive to make them all resolve
like, say, a good Nikon lens, and they don't need to because of
the larger format of the film.

When I first discovered this, it really threw me - my vastly more expensive
Hasselblad optics had _less_ resolving power than my much cheaper Nikon
lenses. This is why ...

Tim Daneliuk [email protected]


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