Related Links:
Depth of Field Tables for Rolleinar Diopters
Diopters Beat Extension Tubes and Macro Lenses
Macrophotography (Bronica) (stacked lenses...)
Pros and Cons of Different Macro Setups
Rolleinar DOF Tables
Swapping Diopter Lenses tips

Diopter lenses are used in photography for:

• closeup photography - the familiar +1/+2/+3/+4 diopter closeup lens kits
• reducing minimum focus distances (fractional diopter lenses +.25, +.5)
• changing the focal length of lenses (front of lens adapters, LF etc.)
• eyepiece corrections for failing, aging, or bad eyesight
  • screw-in 35mm eyepiece diopters for pro cameras
  • variable diopter adjustments on Chimney style viewfinders (Hasselblad)
  • fixed diopters mounted in prism viewfinders on many medium format cameras
  • eyepiece corrections for astigmatism or other vision defects (custom lenses)

Photographers will most often encounter diopter lenses as a kit of +1, +2, +3, and +4 diopter lenses for closeup photography. With failing eyesight, you may also have need to use smaller eyepiece diopter lenses on camera viewfinders or prisms to retain your ability to focus accurately.

These lenses may consist of not just one but two or more elements of glass carefully aligned and cemented together. Greg Erker has prepared a handy Chart of Achromatic Two Element Closeup Lenses. The prices for larger, better corrected multi-element closeup lenses can easily exceed $75-100+, but the performance may be worth it to you.

When you buy certain macro lenses for 35mm cameras, such as the popular Vivitar 90mm macro lenses, you often get a second closeup lens with the primary macro lens. This closeup lens provides the extra closeup range to hit 1:1 closeups using both the macro lens and the diopter closeup, without needing an extension tube. The two optics are matched and work well together. The earlier micronikkor macrolenses required use of an extension tube to reach 1:1, without which they also only reached about 1:2 magnification.

The reason for using multiple elements in such a simple appearing lens is to control various distortions encountered in simple lenses (see Lens Faults Hierarchy definitions).

Using single element, low cost plus-diopter closeup lenses in front of your normal camera lens is likely to produce some very fun and pretty closeup photographs. These photos may be less sharp, especially near the edges of the image, than photos taken with a prime lens. Other lens faults may be discerned with experience or by direct comparison to more costly closeup lenses.

For many more dollars, you can buy brand name, often multi-element closeup lenses from Canon, Nikon, and various other sources that will more closely rival prime macro-lens results. We provide some surprising test results below which show that a high quality closeup lens can beat an extenstion tube on the same lens by a considerable margin in sharpness, linearity, and low aberrations!

In short, you get what you pay for, but even a simple low-cost closeup lens can open up new and fun realms of photography to you!

I believe that it would be a mistake to deny oneself the excitement and fun of closeup photography because you can only afford an inexpensive closeup lens. Buy it, use it, and enjoy it! Conversely, if you can afford a prime macrolens or other macrophotography option, you should enjoy its results that are technically superior to the results from these simple closeup lenses.

Personally, I have a range of extension tubes, bellows, macrolenses, reversing rings, and closeup lenses. Yet when I am traveling light (i.e., most of the time), I often slip in a plus diopter closeup lens or two into my kit.

With your camera lens set at infinity, a +2 diopter lens will bring an object that is 1/2 meter away into sharp focus (roughly 20 inches).

With your camera lens set at infinity, a +3 diopter lens will bring an object that is 1/3rd meter away into sharp focus (roughly 13 inches).

Do you see a trend here? Divide 1 by the plus diopter value to get the distance (focal length) in meters at which the lens will now focus when set at infinity. So a +4 diopter lens will be 1/4 meter, a +10 diopter lens will be 1/10th meter (4 inches), and a +20 diopter lens will be only 1/20th of a meter or about 5 cm. (or 2 inches). Make sense?

So why is this math useful? Using this simple formula (1/+diopter), you can figure out the maximum distance at which each diopter can be used. The larger the plus diopter lens value, the larger the degree of magnification seen. Conversely, the larger the plus diopter lens value used, the smaller is the actual area of the field of view.

In other words, a +1 diopter lens has the least magnification, and hence covers more area. You might use it for a closeup of someone's face. A +4 diopter lens covers a much smaller area, at much higher magnification. You might use it for a flower photograph. A +10 diopter lens has such high magnification that you could only use it for very high magnification covering a tiny area. The head of a bug might be a good candidate.

Knowing these areas of coverage rules will help you decide which +diopter lens to use with your system.

I personally first noticed this problem when looking through a Hasselblad with chimney viewfinder mounted. The Hasselblad chimney viewfinder had a variable diopter eyepiece that could be rotated to provide a range of diopter eyepiece corrections. I discovered that I probably needed +1 diopter eyepiece correction by simply rotating the eyepiece adjustment.

Diopter lenses are part of the solution to these problems. By visiting an optometrist, you can have your eyes checked for astigmatism and related focusing problems. Alternatively, some camera stores will provide a series of diopter lenses in both positive and negative strengths that you can try out with your camera. This test may be useful, and even solve your problem, but you should see an eye doctor to be sure other problems such as astigmatism aren't being covered up!

Astigmatism is a vision defect in which straight lines can be seen as being bent, often in specific regions or directions. One simple if limited test is to look at charts showing a circle of a dozen or so equally sized lines going through a central point. If these lines appear bent at any point when seen with one eye or the other (not both at once obviously), then you can suspect you have astigmatism. Naturally, your eye doctor will have more exhaustive tests to run too.

Astigmatism can also be treated with corrective lenses, with or without diopter corrections. Other vision problems can also be treated by grinding out what is essentially a corrective eye-glass element for your camera optics.

Camera manufacturers often provide a series of corrective diopter lenses in both positive and negative strengths that can be screwed directly into the camera eyepieces. For cameras such as Hasselblad and Bronicas that use prism viewfinders, a series of corrective diopter lenses are also available.

Camera designers make different choices when designing their cameras. This fact helps explain why a +2 diopter corrective lens from a Nikon won't work as for you as a corrective lens on a Bronica prism (even though they may fit).

If you measured a +2 diopter lens from Nikon, Bronica, Pentax, and other manufacturers, you would find they varied considerably in actual diopter strengths (from negative to positive values, even!). The ideal designed focus distance would also differ between manufacturers.

Stated another way, the standard eyepiece in a 35mm camera might be a +5 diopter to properly focus the image for users with normal vision. If you need a +2 diopter correction, you might actually be using a +7 diopter lens on the prism to achieve the desired effect.

Another approach is to just put a second +2 diopter lens behind the existing prism or viewfinder corrective eyepiece. Here again, the focusing distance has to be considered to ensure your eyepieces match your camera. Since stacking eyepieces is like stacking diopter lenses, most photographers prefer to use just one corrected eyepiece.

On another system, they might be using a +11 diopter base value, so to achieve a +2 diopter visual effect, you would need a +13 diopter lens. Now if you found a +13 diopter value lens from another system that could screw into your eyepiece, it would probably work fine (+13 diopters is +13 diopters, after all).

Knowing this, you could potentially save some significant dollars by using a lower cost diopter lens of the appropriate value in place of a higher cost name brand lens. Naturally, most manufacturers would rather you buy their higher cost diopter lenses from them! However, if you are using a Bronica prism, it may be handy to know that Nikon 35mm viewfinder diopter lenses may fit your Bronica prism eyepiece threads.

Diopter lenses on older used systems may be rare and hard to find. If you can find a corresponding size standard eyepiece, just screw it in and enjoy. If not, you have some options.

You can use household cement or other easily removable glue to cement the desired corrective diopter value on your existing eyepiece.

You can cement a corrective eyepiece into a removable rubber eye-cup. Normally, these eye-cups just shield the user from side-lighting during focusing. That advantage is very helpful to folks with older and failing vision in any case. But adding a corrective eyepiece cemented in the eye-cup can be a way to enjoy correct focusing without reducing camera resale value.

See Cons of Diopters by Hermann Graf posting below...

When I saw these figures, I just had to add them to this page. As we might expect, the SMC macro-takumar prime lens had the best edge performance and least color fringing.

What you wouldn't expect was that the 2-element closeup lens and normal 50mm f/1.4 nikkor lens would outperform the same lens used with extension tubes alone! Even more unexpectedly, the closeup lens yielded the sharpest center performance and best overall sharpness performance of all these tested macro setups. The linear distortion of the closeup lens setup was also much less than the extension tube approach. Moreover, the astigmatism and lateral color of the closeup lens approach was very low too.

In short, the closeup lens approach yielded surprisingly good results, especially in terms of sharpness and low aberrations (astigmatism and color fringing). While the closeup lens had more linear distortion than the zooms and macro lenses, this distortion is relatively less important when shooting closeups of natural objects (e.g., compared to IC chips with lines).

Granted, the nikkor closeup #0 lens is a very good one (somewhat pricey, being Nikon), two element achromatic lens. But it is a lot cheaper and more compact to carry around than the lesser performing lenses!

How can this be? The extension tube approach means that the lens is farther from the camera film plane. Where you might have had 80 lpmm resolution at 1/2 lifesize, projecting to 1:1 lifesize on film obviously means less lpmm resolution on the same size piece of film as the magnification goes up. Moreover, the aberrations and distortions of the lens are projected along with the rest of the image to a larger size on film, resulting in degraded performance. A smaller section of the lens (center) is used as well, which may be less than optimally corrected than the overall lens itself.

By contrast, the prime lens remains at the usual distance from the film when a closeup lens is used. So the aberrations of the prime lens are not projected and magnified. Edge corrections are still applied and useful, and the overall optimized lens performance is used rather than just the center.

With a macro-lens, much effort is expended to reduce aberrations and improve linearity and reduce distortion. If you are copying flat documents, a macro-lens will provide the best results. But sharpness in the center may be sacrified to bring up edge sharpness in a tradeoff aimed at a linear response across the entire image field. The simple 2 element achromatic closeup lenses don't make such tradeoffs, thereby providing higher central image resolution (in lpmm) than the edges by a large factor. But as the above table shows, the edge resolution of the 2 element achromat closeup is not bad either!

The additional aberrations introduced by a high quality multi-element achromatic closeup lens are rather minimal, as this study shows.

Once again, the conventional wisdom about closeup lenses and extension tubes is wrong. With the right high quality closeup lens, you can get results that are better than extension tubes. Even better, you don't have to worry about light falloff and exposure factors with your higher quality closeup lens approach. Just meter normally and shoot. You can't beat that - as the table above shows!

You can use plus and minus diopter lenses to change the focal length of lenses. This trick is generally used with view camera lenses only, where the focusing bellows provides the focusing scope to take advantage of this trick.

A simple formula provided by Bob Gurfinkel in a Shutterbug article titled "Lens Attachments Saves You Money". Bob's formula is:

new F = (F/1+DF)

where:
F is focal length in meters
D is power of diopter lens
note D can be + or - diopter value

For example, a 180mm (.18m) focal length normal lens becomes the equivalent of a 220mm (.22m) lens when a -1 diopter lens is used. Conversely, a +1 diopter lens generates a 150mm (.15m) equivalent lens value.

Naturally, you will have to stop down to maintain desired sharpness levels. As with typical diopter lens use, the extra optical element reduces sharpness somewhat. Use of multi-element diopter lenses may help preserve optical quality compared to lower cost single element lenses.

Another issue is coverage. As with teleconverters and other minus diopter lens elements, the coverage will be increased using a negative diopter lens. While we might desire to get a wider angle effect with more coverage, nature only allows us wider coverage with a more telephoto effect. Using positive diopter lenses will reduce coverage, as you might expect since you are getting a wider angle effect.

The effective aperture of the lens will also be changed by using a plus or minus diopter lens. Mr. Gurfinkel recommends changing the ASA instead, so as to retain use of standard aperture settings. He notes that a -1 diopter lens shifts the effective ASA rating from EI 125 to EI 84.

A related and expected problem is that there could be some vignetting, as with any filter. Just as sharpness degrades when you stack diopter lenses in normal closeup work, sharpness degrades when you stack them in this application too.

Many view camera users would rather buy more prime lenses than reduce their sharpness with such a lens. However, there are times as in portraiture where a less sharp, more telephoto image would be preferred. For such cases, here is an inexpensive alternative solution.

One unusual use for diopter lenses is to shift the effective focus point of the lens. A good example is the series of lens mount converters offered by various dealers (see Lens Mount Converter FAQ).

Different cameras are designed with different lens mount to film plane distances, known as the lens registration distance. When the lens is designed for a longer distance than the new camera body mount, a purely mechanical mount adapter is possible.

For example, a 105mm Mamiya RZ lens can be mounted and focused on a Bronica S2A with a circa 82mm lens registration distance. You have 105-82 or 23 millimeters for building a mechanical mount adapter.

But you can't simply physically mount a lens designed for the Bronica 82mm mount distance on a camera body designed for a 105mm lens registration distance. The extra distance acts like an extension tube 23mm long on the Bronica lens. As with any extension tube, you lose infinity focus and can use it only for closeup work.

The solution is to use an optical mount converter. Typically, these optical mount converters are in effect minus diopter lenses. These negative lens elements increase the focal length slightly.

In an example from Herbert Keppler's SLR Column (Popular Photography 1994 p.62), the converter shifted the given lens (Pentax PK) some 17% when used on a Minolta Maxxum. So an 18-28mm Pentax PK zoom acted like a 21-31mm zoom on the Minolta Maxxum.

This teleconverter effect is quite small compared to even the +40% shift achieved by a 1.4x teleconverter. Since the teleconverter effect is so small, the light loss is equally small (about 1/4 stop) and is usually ignored or factored out by the internal SLR metering.

I find this an intriguing opportunity. Obviously, a negative diopter lens is able to change the plane of focus to a desired longer value. So a Canon 42mm lens registration distance lens can be used on a nikon camera despite its circa 46.5 mm lens registration distance - if you use an optical lens mount converter.

Such an optical converter will suffer from some modest image degrading effects (as with any diopter lens). Vignetting might also be a problem needing careful addressing. Size of rear lens elements would have to match the converter mount optics. The position of these optical lenses might require a stand-off mount (as with most teleconverters). Or you might be able to simply mount a small and thin diopter lens at the end of your existing optic, possibly in a rear filter holder element?

Still, I find it intriguing that such a converter option might be and is used to adapt shorter focusing lenses onto longer lens mounts. Could it be possible that a shorter mount Kiev-88 lens (82.10mm) could mount onto a Bronica S2a (101.70mm) simply by using what is in effect a diopter lens teleconverter and some mounting hardware? Hmmm...

W.J.Markerink's Lens Registration Table Page

Notes:

Sources for negative diopter lenses include Telek by Kodak in -1, -2, -3, -4 zeiss distar -1/2 to - 4 1/2 diopters from R. Kingslake Lenses in Photography, 1963, p. 77.

Related Postings:

Hi Phil. The diopter units that you refer to relate to distance correction not the kind of magnification correction associated with reading distances. Check your prescription and the talk to your photo dealer to see what unit comes closest to your needs.

>Subject: EyePiece Diopters
>From: "Phill Davis" [email protected]
>Date: Sun, Jul 5, 1998 
>
>Hello,
>    My eyes aren't as good as they used to be, I use the drugstore-type
>reading glasses.  A +1.25~1.75 seem to work well depending on how close to
>my eyes the work I'm doing is.
>    When I look into the prism-finder on my Bronica, things aren't as sharp
>as I'd like to see them.  Figuring that that's what my reading glasses are
>for, I pop them on, and... for some reason, that doesn't seem to do the 
>trick.  When using the waist-level-finder, and popping the magnifying lens
>up, things are great.
>    Therefore I wonder is there any advantage in finding a 1.(whatever)
>diopter for the prism?  If my reading glasses don't do the trick, is a
>diopter going to work differently?  Maybe the built-in magnifying lens is
>something on the order of a +5.0 or somesuchother?
>    Any advice would be appreciated.
>Later,
>Phill
>

Hi Phil, The diopter units for correction that you refer to are for distance not reading.The best thing to do is to refer to your distance prescription and then talk to your photo dealer to find what unit {They usualy are availiable from +5 to -5 diopters} most closely matches that prescription.

From: [email protected] (David Barr)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: EyePiece Diopters
Date: Mon, 06 Jul 1998

Last year Phil I went through the same problem - According to the Hasselblad service centre in Ontario you have to have your eyes checked at 5 feet. The diopter correction at this distnace is what to use to correct the camera eyepiece.

You can use an add on diopter filter but I opted for the replacement eypiece for the viewfinder. The normal eyepiece is ( if memory serves me right) +11.5 and I have a new eyepiece which is + 12.5 diopter. It works wonderfully.

The Bronica repair centre in your area should be able to give you the right details about having your eyes checked for their equipment!

I also bought a Pentax adjustable lupe for viewing my transparencies.

Regards David

From: "Byron Marr, D.O." [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: EyePiece Diopters
Date: Mon, 06 Jul 1998

I am not an eye doctor, But this is how it was explained to me.

The best analogy of what is going on is a theater. you are looking at a screen that has a projected image that can be altered by focus. If your eyes are in focus to the screen...you can then focus the lens correctly The distance of your view finder does not change. So when you are looking into the view finder..you need to be focused onto the screen.

How? Well take the lens off and point the camera to a light subject..white wall..looking through it and then try diopters until you get the "grain" of the focusing screen in focus. You should see a more clear type of grain..like the grain focus while enlarging..when you are in focus. This is obviously for the screw in type of diopters and no the factory modified prism therefore you will need to go somewhere that carries the diopters and try them. Use your eye glass prescription as a starting point...but keep in mind that eye correction can change rather quickly and that focal distances may be measured at different lengths while having eye exams. Astigmatism is hard to match based on eye exam prescriptions as well.

When you call your eye doc to get your prescription..ask if you have an astigmatism..that will be important if you go with a comercially altered prism.

Date: Wed, 23 Sep 1998
From: "Ben R. McRee" [email protected]
To: [email protected]
Subject: [Rollei] Easier Waist-Level Focusing

When I recently went in for an eye exam, my doctor and I decided that it was time for bifocals. Among other things he asked about my hobbies and said that because of the way cameras were designed, bifocals wouldn't help with photography. Clearly he didn't have waist-level finders in mind. I don't know what the design difference between prisms and waist-level systems is, but I am amazed at the improvement the new glasses have made in focusing my TLR! I now find focusing much quicker and more accurate. This has been a wonderful and unexpected benefit of one of the rites of passage into middle age.

From: [email protected] (MrLens)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: How do I figure diopters?
Date: 18 Sep 1998

>Can I get this info from my
>eyeglass prescription? If so, I have looked at the script carefully but
>I see no mention of diopters

The numbers on your prescription are diopters (except the axis for astigmatism). The first number (usually under the word "sphere" or "sph") is the amount of correction for nearsightedness or farsightedness (-) for near, (+) for far. The second number (under "cylinder" or "cyl") is for astigmatism... hopefully this is not more than 1.00, or you may still have problems focusing because eyepieces for cameras do not come in cylindrical (astigmatism) corrections. The last number is the axis of the cylinder (where, between 0 and 180 degrees, the lens is positioned to correct the astigmatism); this number has no bearing on the diopter value.

To be most accurate, you would algebraically add 50% of the cylinder to the sphere. For example, if your prescription reads: +2.50 -1.00 x 180; add half of -1.00 to to +2.50; +2.50 +(-0.50) or +2.50 - 0.50 = +2.00.

You likely also have something called "Add" on your prescription (judging from your aging comment); this is the amount of + power added to the sphere number in your prescription to allow you to read. For example, +2.50 -1.00 x 180, Add +2.00 means that the power of the lens that lets you read is +4.50 -1.00 x 180 (+2.50 +2.00 = +4.50)

Hope this helps. E-mail me privately if you want more detailed help.

Al Lens (the name comes in handy sometimes!)
Al Lens
Pro-lens Photography
www.pro-lens.com

From: Rick Dawson [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Figuring diopters
Date: Fri, 18 Sep 1998

Thanks to all who responded to my diopter question. I think I have a handle on how to do this. This is my favorite response (although they were all good):

Posted with permission of author:

Rick,

1. Do not take the advice of MrLens! Your prescriptions are for correct corrections at infinity, while you need to see clearly one meter away with most viewfinders including the P67, so the amount of correction is different. Another way to say this is that if you check your manual they will say the default strength is -1.0, even for the perfect eyes.

If you have a computer glass prescription, it will usually work. And keep it in mind that a little under correct is much more comfortable than over correct to our eyes.

2. The round shaped Nikon diopters for N8008/N8008s/N90/N90s fit the Pentax 6x7 or 67, and is cheaper and wildely available. So your best bet is to bring your P67 to a large camera shop, asking for the Nikon diopters, and test several of different strength out out. This way you are sure you get the best possible for you.

I use the -3.0 Nikon on my P67, while my regular glass for my left eye is -3.5, by the way. Also I do not believe any diopter piece for camaras correct for astigmatism.

Regards,
Leping

LEPING ZHA, Ph.D.
Radiological Imaging Laboratory (RIL), Toshiba America MRI, Inc.
E-mail: [email protected]

From: [email protected] (Charley Harp)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: How do I figure diopters?
Date: Tue, 22 Sep 1998

By all means *try* any corrective lens before purchasing.

To figure diopters remember the definition: the diopter rating of a lens is the inverse of the focal length in meters. Thus a +2 diopter lens is a (+ or convex) 500 mm lens and a -3 diopter lense is a (- or convex) 333 mm lens.

I'm surprised that your eyeglass prescription does not indicate diopters directly -- mine does (+2 left, +2.5 right, both nearsighted). *BUT* that doesn't mean that I need a +2 diopter lens for viewing! Truth is, with the apparent distance used in all the SLR's I use, I remove my glasses and view the screen *UNAIDED*. With my glasses on it's a struggle to focus on the apparent image!

Charley Harp [email protected]

rec.photo.technique.misc
From: Jack Daynes [email protected]
[1] Re: Autofocus + close up lens
Date: Sat Oct 31 1998

ChipCurser wrote:

> Hi,
> I hope this is the right place to post this.  anyway, I have a Nikon  N70 with a
> couple of nikon zoom lens.  I would like to know if I can use close up  lenses on
> them and will the auto focus work with them on, or would I have to focus
> manually.
> Thanks in advance.  

Chip,

You have options. If you go with attachments to the front of the lens (filters), then AF and metering are not affected. If you go with extension tubes (between t he lens and camera) you can go with Kenko tubes and AF and metering will still be O K (e.g. the camera will compensate for light loss). If you go with Nikon tubes, you will have to manually focus, but TTL metering should work.

I'm told there are multi element front of the lens attachments that are quite nice, but I've not tried them as yet.

Hope this helps,

--
Jack

From Nikon Digest:
Date: Tue, 27 Oct 1998
From: [email protected]
Subject: Re: Question about diopters

Chris,

To reduce eye fatigue, all Nikon cameras are engineered with a -1 diopter value. Theoretically if your diopter is -1 than you shouldn't need any additional correction. In addition, if you can easily see something that is one meter away then you also shouldn't need any correction; all Nikon viewfinders are designed so as if you were looking at something one meter away.

Ed

Ed Yost
M&M Photo Source (Photographic equipment and supplies)
800-245-6873

[Ed. note: some posters have suggested Lenscrafters or other eyeglass makers can also do diopter lens making for camera users...[

From Medium Format Digest:
From: Tim Brown [email protected]
Subject: Response to 6X7 Diopters MAKE YOUR OWN cheaply!
Date: 1998-10-23

I periodically just have the lenses in my glasses replaced and have the old lenses cut down to fit on my various (Canon, Mamiya) cameras.

From: [email protected] (Herphoto)
Newsgroups: rec.photo.equipment.35mm
Subject: Re: How to buy a close-up lens attachment?
Date: 2 Nov 1998

> I have bben looking at several close-up lens attachments but I don't
> understand the numbers eg #0,3T,4T etc. Can someone explain these to
> me?
>
> I plan on using the above on either my Nikkor 35-80 or the 70-300 ED
> for macro photography.
>
> BTW, the filter size of the 70-300 ED is 62mm whereas the 35-80 is
> 52mm. Can I use the BR-5 62/52 adaptor ring (Nikon brand) so that I
> don't have to buy 2 sets of filters. Is the 62/52 designed for this ?
>
> Thanx.

The No. 0,1,2, 3t and 4t are 52 mm filter size. The diopter ratings are .7 for the 0; 1.5 for the 1 and 3t; and 3 for the 2 and 4t. The 5t and 6t are the same diopter ratings as the 3t and 4t respectively, but are 62 mm in size. All of the t dipters are two element and provide much better image quality than single element diopters do. I use a 5t on the nikkor 75-300 AF and it is a really nice combo. Maximum magnification is just short of life size when the zoom is used at its minimum focusing distance and 300 mm. Best bet would be to get the 5t or 6t for your 70-300 and use the step-down ring to mount the filter on the 35-80. However, you'll probobly seldom do this since diopters do a lot more for you magnification wise on longer focal legnth lenses.

Billy Gorum

rec.photo.equipment.medium-format
From: [email protected] (Vickiedogs)
[1] Re: kowa super 66 diopters
Date: Sat Nov 21 1998

I ues a +2 diopter in my 90 degree kowa head I used one from pentax 6x7 all you have to do is to loosen the eye peice on the back of the peice and put the diopter between the eye peice and the prism and hand tighten it to hold it in place works fine

rec.photo.technique.nature
From: [email protected] (PBurian)
[1] Re: Macro lenses vs Extension Tubes
Date: Sun Nov 15 1998

I have always felt the best alternative to a true Macro lens was:

A 70-300mm zoom plus a double element supplementary close-up lens like the Nikon 5T. (resembles a filter with magnifying glass.)

Peter Burian, Editor
Shutterbug's OUTDOOR & NATURE Photography
See also www.outdoorandnature.com

From: [email protected] (Neuman-Ruether)
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Macro lens or close up attachment?
Date: Thu, 19 Nov 1998

Jeff Rester [email protected] wrote:

>I currently own a Canon 28-105 zoom and I am interested in doing some
>close ups of flowers and such. I was considering buying a Canon 50mm
>macro lens ($300) or the Canon close up lens attachment (CU250D) ($85)
>for the 28-105 zoom. Does anyone have any experience with either of
>these? Price is a consideration and I don't believe that I would be
>interested in getting 1:1 magnification.  Any comments and experiences
>would be appreciated.    

If high magnification and flat-field are not requirements (and it looks like they may not be for you...), and if smallish stops can be used (with the assistance of a tripod or TTL flash), an achromatic (2-element) close-up lens added to a good zoom can give excellent results. (You can find some high-magnification images taken with achromats (added to non-zooms) on my web page, under "photographs", "Bugs"...)

David Ruether
[email protected]
[email protected]
http://www.fcinet.com/ruether

From: "Michael Covington" [email protected]
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Macro lens or close up attachment?
Date: Thu, 19 Nov 1998

An even cheaper close-up lens attachment (the kind they sell with filters at camera stores) would do the job.

Why? Because flowers are not flat subjects, so you do not need flatness of field or complete absence of distortion the way you would if you were copying artwork or the like.

--
Michael A. Covington - Artificial Intelligence Center - University of Georgia http://www.ai.uga.edu/~mc http://www.mindspring.com/~covington

Date: Tue, 24 Nov 1998
From: [email protected] (Rudy Garcia)
Newsgroups: rec.photo.technique.nature
Subject: Re: Macro lens or close up attachment

...

I've been accused of total disregard of optical theory and God knows what else (High crimes and misdemeanors?).

Ok, I'll try this one more time with a simple example.

First, lets look at how closeup lens attachments work.

Say you take a 100mm focal length lens, set to f-11 and put a +1 diopter on it.

A closeup diopter lens changes the overall focal length (makes it shorter).

A 100mm lens is equivalent to a diopter power of +10. Since total diopter power is simply the sum of the diopters, the total is +11. Now converting that back to focal length

Focal Length (mm) = 1000/diopter power = 90.9 mm

So, the original 100mm lens with a +1 diopter is now really a 90.9mm lens, able to focus down to ~3 ft (1 m), with the lens set to infinity focus.

The magnification of the rig can be computed in a couple of ways, one is to divide the lens focal length by the diopter focal length. In this case Magnification is 0.1X .

Now, whats happened to the aperture? It was f-11, so the diameter of it was:

Diameter = Focal length/11 ~ 9.1 mm

The aperture diameter hasn't changed just because we slapped on a suplementary closeup lens. It is still 9.1 mm. But the combined lens-diopter is really 90.9mm in focal length, so the marked f-11 on the lens barrel is really an effective f-stop of:

feff = 90.9mm/9.1mm ~ f10

Unarguably f-10 has slightly less DOF than f-11, so closeup lenses tend to give you slightly less DOF than the marked f-stop aperture (because the effective f-stop is a smaller number).

Now, lets look at extension tubes.

For the same 0.1X magnification, we need a paltry 10mm worth of extension tubes. This will cause some light loss as people have pointed out. It also changes the effective f-stop. Assuming a pupillary magnification factor of ~1 (pupillary magnification is the ratio of the entrance pupil to the exit pupil), the effective f-stop is given by:

feff = marked f-stop * (M +1) = f12.1

Unarguably f-12.1 has slightly more DOF than the f-11 marked aperture, or the f10 effective aperture of the 100mm lens set at f-11 with a +1 diopter on it.

The effective aperture change IS REAL. Those of you familiar with how DOF formulae are derived from geometric ray tracing diagrams can recall the cone diagram used, with the exit pupil as the base of the cone and the angle at the apex (usually at the film plane) being used to calculate DOF, using a permissible circle of confusion.

The DOF equation, using the effective f-stop is given by:

DOF = 2* (feff * COC/(M^2))

Where DOF is centered around the subject plane, COC is the assumed circle of confusion and M is the magnification.

Bottom line. For a given marked f-stop, tubes do give slightly better DOF than closeup lenses.

--
Use address below for Email replies. Address on Header is bogus to defeat AutoSPAM.

[email protected]

From: J Greely [email protected]
Newsgroups: rec.photo.technique.nature
Subject: Re: Macro lens or close up attachment
Date: 24 Nov 1998

[email protected] (Rudy Garcia) writes:
Unarguably f-10 has slightly less DOF than f-11,

You can't compare f10 to f11 directly here, since they're on lenses with different focal lengths. At the same object distance, the 90.9mm lens set to f10 has *more* DOF than the 100mm lens set to f11. Your statement does seem to be true when the two are compared at the same magnification.

-j

Date: Wed, 25 Nov 1998
From: [email protected] (Rudy Garcia)
Newsgroups: rec.photo.technique.nature
Subject: Re: Macro lens or close up attachment

...

In order to keep the math simple I used a meager 0.1X magnification in both cases. Since the magnification is the same for both cases the tube setup has more DOF. Albeit, in the example I gave, the difference is not very significant but if anyone cares to work up the numbers for say 1X magnification, they'll be surprised at the difference.

--
Use address below for Email replies. Address on Header is bogus to defeat AutoSPAM.

[email protected]

rec.photo.equipment.medium-format
From: [email protected] (PWestenber)
[1] Re: Kowa Super 66
Date: Sat Jan 09 1999

Oh yes there are . I had my repair man unscrew the eye peice on my 90 Degree finder and I took a +2 diopter I had left over form the Pentax 6x7 . laid it inside the prism and screwed the eye peice back in just tight enough so the diopter dosn't move around works great

rec.photo.equipment.35mm
From: [email protected] (Thomas Bantel)
[1] Re: Extension tubes vs. close up lens
Date: Thu Mar 04 1999

[email protected] (Ara Kotchian) writes:

> With extension tubes you don't have to deal with loss of optical
> quality but you have to deal with loss of light. ...

Actually, you have to deal with loss of optical quality as well. Why? Because you add extension beyond the point, the lens was designed for. Otherwise, there would probably be not much demand for macro lenses. It depends on the lens, the amount of extension added and the quality of the close up lens, which one will give better results. Especially lenses with internal focusing (IF), which most modern zoom lenses have, will most of the time work not very well with extension tubes. A good, two element, achromatic close up lens will give better results then.

Thomas Bantel

From: [email protected] (Tom Rittenhouse)
Newsgroups: rec.photo.misc
Subject: Re: Correction lenses
Date: Thu, 4 Mar 1999

Aju post:

>Hi all,
>
>I am interested in getting a correction lens since I am slightly
>short-sighted (1.0 dioptre), and finding that I am having to rely on my
>camera's AF for focussing. All my local photo shops don't stock them,
>but are willing to order them.
>
>Anybody out there who is using or has used correction lenses? Can I have
>your opinion on them, since I don't want to commit myself into ordering
>them if they aren't brilliant.

Aju, If you are slightly near-sighted and don't have an astigmatism problem, you can probably focus OK just by taking off your glasses.

SLR cameras tend to have their focusing screens set for about one meter apparent distance from the eye. A diopter lens works just like the bifocal lens in eyeglasses, it adjusts your vision for that one meter distance. If you can focus your eye to one meter, with or without grasses you have no need for the diopter.

For those of us who have lost the ability to focus at that one meter, or who have astigmatism those diopters are a godsend. What I usually do is wear my contacts for distance vision and astigmatism correction and use the diopter to allow me to focus on the viewfinder screen. And use a pair of drug store reading glasses for other close up situations.

The diopter will not change the brightness of the viewfinder at all. All it will do is allow your eye to focus at that one meter.

By the way you can also see your optometrist about custom diopters that will correct for astigmatism as well, but they would have to be mounted in a rotating device on the camera so you could shoot both vertical and horizonal. Years ago Exacta made a device for this which was often adapted to other SLRs.

Hope this answers most of your questions and provides useful information to others.

--
Tom Rittenhouse (graywolf)

From: "Rick Rieger" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Medium format recommendations
Date: 24 Mar 1999

So does Bronica. The GS-1 is a way-underrated camera. I have a GS-1 system and have been very pleased. The camera is no heavier than the Pentax 6x7 but offers interchangeable backs. As for closeup, I have the 18mm and 36mm extension tubes and also use the Nikon 5T and 6T dual element diopters. Even though these diopters are 62mm, they don't seem to vignette on the Bronica 72mm filter thread lenses. I can get to 1:1 magnification. There is a bellows unit, but I don't have one.

Used, you can get some reasonable deals on this system.

rec.photo.equipment.medium-format
From: "Ron Walton" [email protected]
[1] Re: Dioptor for Mamiya C330 Prism
Date: Tue May 11 1999

I'm using a diopter made for Canon EOS 10s/Rebel G on my Mamyia 645.

Ron Walton
Visit the BPC http://www.bpc.photographer.org

From: "Fred Whitlock" [email protected]
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Macro lenses?
Date: Wed, 2 Jun 1999

Yes, even though macro lenses are designed to focus close, they will also focus to infinity. Since they are optimized for close focus they don't perform quite as well at infinity as they do up close nor do they perform quite as well as a non macro lens at infinity focus. Nevertheless they can be considered general purpose lenses. Plenty of good photographs have been made with macro lenses focused at infinity. Good shooting.

Fred
Maplewood Photography

From: Len Cook [email protected]
Newsgroups: rec.photo.technique.people
Subject: Re: Photography and eye-sight
Date: Wed, 02 Jun 1999

The "distance" correction portion of bifocals isn't often appropriate for use with the camera eyepiece. Most SLR prisms are set for a viewing distance of about 30". That is, the image of the ground glass appears to be 30" away from the eye. For us eyeglass wearers, that's a really awkward distance. The top half of bifocals, for example, yields best correction at distances considerably further than 30". The bottom half (the "reading" portion) is usually corrected for distances much closer than 30".

Camera prisms, therefore, fall into the rather large gap between those two corrections. My strategy has been to buy drugstore glasses with a correction of about +2.25. That correction works just fine for me, allows me to focus easily, and still lets me see nearby (room-length) without too much discomfort. The glasses are cheap enough so that when they get trashed by the eyepiece pressing against them, I toss 'em and buy replacements. I put one such pair in each of the bags I use for different formats. I also tend to press the camera against my face rather hard at slow shutter speeds. I'm hoping that will help keep my nose from getting too big. So far, that part of the plan has been a complete failure.

Len

JGC wrote:

> I have had a similar problem.  With my eyeglasses on I focus my Nikon  FG and
> it looks great...till I get the photos back - out of focus!  I broke down
> and bought an auto-focus camera, the F70, but I am not so happy with it.
> (You have to be a genius to remember which button or knob to turn!  Too  much
> for me to keep up with.)  I am told by my opthalmologist that I should  focus
> my manual camera, looking through the top of my bifocals (which is
> correction for distance in my case).  I hope your friend's success is  better
> than mine.

--
Len Cook

From: Andrew Koenig
To: [email protected]
Sent: 7/4/99
Subject: [NIKON] eyepiece correction lens

John Albino said:

> The F5 eyepiece is in the current Nikon catalog -- part # 2950 NAS, I's
> called a Neutral "0" Eyepiece Correction Lens for F5, F3HP/F3. List price
> is US$23.

I don't think this statement is correct. Nikon generally builds in a -1 diopter correction into their finders, which is equivalent to the finder forming a virtual image at an apparent distance of 1 meter. The reason for this is that more people are nearsighted than farsighted, so more people can see a virtual image at 1 meter sharply without glasses than can see a virtual image at infinity sharply.

The "neutral correction lens" is actually a +1 diopter lens, because all the Nikon eyepiece correction lenses are rated for the combined correction of lens + finder. The reason for this is so that if you know the prescription for your glasses, ordering the same number in a correction lens will give the right answer. So, for example, if your glasses are -2, you will order a -2 correction lens, which is really -1. Combine that -1 with the -1 built into the finder and you wind up with -2, which is what you wanted.

The foregoing discussion implies that if you want to replace a lost eyepiece, you should look for something like "replacement eyepiece (-1)", not the neutral correction lens. Please verify this claim independently, though - -- because although I am fairly certain it is true for the entire Nikon line, I might be mistaken.

Regards,

Andrew Koenig

From Nikon Mailing List:
Date: Thu, 8 Jul 1999
From: "Thomas, John" [email protected]
Subject: [NIKON] long,cheap zooms, and diopters

Hi (again) folx,

In #181, WanGong the Kelvin asked about the weight of the AFED 70-300; it's 515g. It is *very* hand-holdable.

He also asked about the 5T and 6T diopters that I'd mentioned in a previous post. Roland Vink posted the following information to the Digest about a year ago:

/ begin quote

Nikon closeup lenses:
No 0    0.7 diopter, 52mm
No 1    1.5 diopter, 52mm
No 2    3.0 diopter, 52mm
No 3T   1.5 diopter, 52mm
No 4T   2.9 diopter, 52mm
No 5T   1.5 diopter, 62mm
No 6T   2.9 diopter, 62mm

The focal length of a filter is 1000/diopter value

Closeup lenses 0, 1 and 2 are single element filters recommended for lenses up to 55mm. The others are two element achromats recommended for telephotos, which are of very high quality.

I would get the achromats since diopters give greater magnification with telephoto lenses, and there is no reason they can't be used with shorter lenses as well.

/end quote

Regards,

JT ...

rec.photo.technique.nature
From: Bob Flood [email protected]
[1] Re: close up diopters
Date: Thu Aug 26 1999

Peter Mikalajunas wrote:

> A bellows.   Some allow full aperture automation, some don't.
> Pro: usually allows the max in magnification control.
> Con: hard to use in the field, takes a bit to set up.

Let me add another con: most bellows have a minimum fold-up size that is significant, which means there can be a substantial gap between the closest you can focus a lens without the bellows and the farthest you can focus the same lens with the bellows. This leaves you with an unusable range that may not be trivial (it certainly wasn't for me).

rec.photo.equipment.35mm
From: [email protected] (Chuck Ross)
[1] Re: Nikon Diopter - Prescription v. Diopter Number
Date: Wed Sep 29 1999

Well, let's see...it's a little tricky. Nikon sets their viewfinders at a minus 1.0 diopter. So, theoretically, if you add -1.0 diopters from your eyeglass prescription it should work out to a diopter number that is the correct diopter value to bring a -1.0 to the value of your eyeglasses. For example, let's say your distance vision prescription is a +2.5 diopters. So, -1.0 plus 2.5 = 1.5 diopters.

BUT WAIT: it doesn't work that way. You then need to subtract another 1.0 diopters from that value, coming up with a value of +0.5 diopters.

Why? I'm not sure, but there's something about Nikon's diopter lenses that require this, and I know that the above procedure works.

To simplify a bit more, my eyeglass distant vision is +2.5 diopters. For me to be able to see the viewfinder clearly, I need a +0.5 diopter lens. That works amazingly well, and I would (almost) guarantee that if you use those values, or substitute other values for your prescription, it would work.

But still the best way to do it is to actually try the diopter lens on your camera. Some people's eyes accomodate better than others, and I find that a difference of 0.5 diopter one way or the other does not work. This is easier said than done; many dealers do not stock all the diopters for all the Nikon cameras: Even B&H doesn't always have the one you need in stock. If they do have several different diopters that will fit the camera, it might be a good idea to order several and return the ones that don't work.

It was for this exact reason, the difficulty of getting the correct diopter, that I exchanged my N90s for an F100, which has built-in diopter correction, solving all the problems, bingo! Why they don't build diopter correction into all the cameras right off is a very puzzling thing.

For me, I simply cannot see thru most P&S cameras. Absolutely blur-ville. The number of P&S cameras with built-in diopter eyepieces is very low. I did find a little Pentax IQ-80 or some such that had it, and it works well.

Incidentally, the FG takes the same diopter as the N70. I am currently selling one on Ebay; it's a +0.5. If you're interested in that strength, e-mail me and I'll give you the auction number.

"Jim" [email protected] wrote:

> I would like to get a diopter for the finder on my FG.
>
> I have the prescription for my glasses, is there a formula or chart for
> figuring what diopter you need based on your eyeglass prescription?
>
> Thanks in advance,
> Jim  

From Rollei Mailing List:
Date: Mon, 4 Oct 1999
From: "Thomas A. Frank" [email protected]
Subject: [Rollei] Diopter adjustments, very little Rollei content

>+/- 3 diopter adjustable eyepiece - toss them glasses!

Not when you're -6/-8. :-(

I'm always amazed that the photo industry continues with this feature. I asked my optometrist, and he tells me that if you add up all the eyeglass wearers either greater than +/-4 or with an astigmatism, you have well over 50% of all wears. Which makes me wonder just how many people the photo equipment industry thinks it is helping.

Of course, if you do take off the glasses to use the camera, you then run the risk of not seeing something important. And if you do, you then sue the camera maker for creating the hazardous situation.

Not a feature I would provide, were I, say, Rollei. I'd rather spend the effort to make the finder useable by eyeglass wearers - something that Hasselblad has singularly failed to do. Haven't tried the 6000 series yet.

Tom Frank

From Rollei Mailing List:
Date: Mon, 04 Oct 1999
From: Richard Knoppow [email protected]
Subject: Re: [Rollei] Diopter adjustments,

....

The problem is that making a finder usable for people wearing spectacles is difficult. The requirement is long eye relief, i.e. how far your eye can be from the finder and still see the whole image. Long eye relief eyepieces are made for all sorts of optical instruments. They are a necessity for gunsights, but are expensive to make. I think that is why so few camera makers supply them.

I am old enough to have virturally no range of accomodation, that is , my eyes are pretty much fixed-focus. I am also near sighted. So, I have a problem with cameras like TLR Rolleis and even Speed Graphics. I have to take my glasses off to see the GG in the Rollei or to see the settings on the camera and put them on again to see the subject or to see through the finder on the SG. When I wear contact lenses it can be very difficult.

Frankly, I prefer to be able to see through the finder without glasses. I actually have two diopter correcters for my old Nikon, one for my uncorrected right eye, another for use with my contact lenses. Using this finder with glasses is not really possible due to the short eye relief as complained about above.

Some day someone will figure out how to make replacement eye lenses which focus, or perhaps how to fix the hardening of the crystaline lens of the eye so it can focus again. I am not holding my breath.

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

From Nikon Manual Mailing List:
Date: Sun, 14 Nov 1999
From: Rick Housh [email protected]
Subject: Re: diopters page (for MF lenses etc.) formula to change focal length..

....

Hi, Bob.

I thought your page on diopters was excellent. I wasn't surprised to see that the results of the Nikkor 50mm f1.4 and Nikon #0 diopter were even better than some macro lenses, as I have been using a #0 with a 105mm f2.5 for some time with excellent results, where a little linear distortion is tolerable. I have also had very good results with a 100mm f2.8 Series E. As stated, the resolution is great, but you do need to stop down a little, as the #0 is optimized for shorter lenses, and any faults are magnified some with a longer lens, but I find the longer working distance an advantage with flowers and the like.

I don't think the #0 is a two-element optic as stated, though, and I don't think its diopter is +1, as listed in the chart. Nikon lists it as a single element (only the ones with "T" after the number are multi-element) and its diopter as +0.7.

- Rick Housh -

From Nikon Mailing List:
Date: Mon, 10 Jan 2000
From: "Owen P. Evans" [email protected]
Subject: Re: [NIKON] Nikon Close-Up Lens Attachments Designation

Nikon Close-up lenses are as follows:

lens name/filter size/diopter value

0 - 52mm - +0.7
1 - 52mm - +1.5
2 - 52mm - +3.0
3T - 52mm - +1.5
4T - 52mm - +2.9
5T - 62mm - +1.5
6T - 62mm - +1.5

The T lenses are the best quality due to their dual optical elements.

Regards,
Owen

Date: Mon, 24 Jan 2000
From: "Fred Whitlock" [email protected]
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Achromatic Close-up Lenses

Achromats work quite well. We use them regularly with medium format for tabletop catalog work. The results will surprise you. Don't stack them.

Fred
Maplewood Photography

....

From Rollei Mailing List:
Date: Sun, 14 Nov 1999
From: Bob Shell [email protected]
Subject: Re: [Rollei] Rollei SL 35 lenses

Excellent camera! Particularly the German made ones. When they moved production to Singapore they had some shakedown problems. Early Singapore ones (and unfortunately I don't know serial number range) have beryllium copper meter contacts which were not quite right and not springy enough, so after pressing the metering button a number of times they would bend and not make contact. A bear to get to them to replace them, and I doubt anyone has parts anyway. You can bend them and cure the problem for a while but they always bend back and the meter stops working.

Also, some of the early Singapore ones have the eyepiece lenses ground to the wrong diopter value and the focusing screen is impossible to see clearly for most people. I used to replace them with eyepiece lenses from Minolta SRT series, which just happened to fit perfectly.

If you get one of the late Singapore ones or a German one it should be fine.

The SL350 is much nicer, but incredibly rare. The only one I ever saw is one that Bob Salomon loaned to me for a while. It looks like the SL35 but is more refined, has a hot shoe, and offers TTL metering with QBM lenses from the second and third series.

Bob

....

From Hasselblad Mailing List;
Date: Sat, 25 Mar 2000
From: Steve Grimes [email protected]
Subject: Re: Proxars

Save yourself some serious money by substituting a plain aftermarket set of "close up filters" which are essentially the same thing. All these things are merely "plus diopters" or spectacle lenses adapted to fit the front of the lens. (The numbers: 0.5, 1.0, etc are the same numbers as found on drugstore spectacles.) In fact, the lenses from drugstore plastic spectacles can be pressed into service as close up filters if you are on a really tight budget or just want to experiment.

(Granted, the genuine Proxar are a very high quality item; its just that high quality doesn't make any important difference for this accessory.)

S.K. GRIMES -- FEINMECHANIK -- MACHINE WORK FOR PHOTOGRAPHERS
+ For more info-- http://www.skgrimes.com.

----- Original Message -----

From Hasselblad Mailing List:
From: Owen P. Evans [email protected]
To: Hasselblad [email protected]
Sent: Saturday, March 25, 2000
Subject: Proxars

> Hi all,
> I have never used the Proxars so I am asking some questions which I can't
> find an answer to so far.
> I have a CF 80mm f2.8 Planar and I want to make close-up photos of flowers.
> Right now, extension tubes are out of my budget but a set of Proxars is
> available at a second hand store for a good price. ( 0.5;1.0&2.0 for $500.00
> Canadian or $330 US currency )
> What magnification will I achieve with each of the Proxars on the lens? Is
> there much depth of field with these Proxars ? There are some tiny scuffs on
> all three Proxars which won't come off; will these show up on the photos?
>
> Thankyou,
> Owen

Date: Fri, 07 Apr 2000
From: [email protected] (Peter Mikalajunas)
Newsgroups: rec.photo.technique.nature
Subject: Re: closeup lenses

Brat [email protected] wrote:

>Hi everyone.
>I was just looking intothe matter but couldnt find
>any god articles/info about them - does ANYONE
>ever use close up lenses? And why/why not - what's
>the quality - I know it's less then a prime but is
>it usefull at all? I thought it to be a cheap
>alternative of macro lens oe even an X-300mm lens
>(or does that sound crazy? :)
>So, whats your opinion/findings?
>Brat

Close-up lens can yield very good results. It all depends on what you are trying to do. I always carry a set in my bag, just in case.

For a simple, cost effective way to do occasional close-up work they are great.

Anything less than 1:1 magnification should be considered close-up. This is to distinguish it from macro and micro photograhy.

There are a host of options for close-up work, eg, macro lenses, diopters, extension tubes, reversing rings, lens to lens adapters, bellows, etc. There is no hard and fast rule about which should be used when. Though some make more sense, eg, it makes more sense to use a bellows in a studio than in the field. You should also be aware that some of these can be used in combination, eg, 1.4x tele-converter with a prime lens and a diopter can be very effective.

I have found for best results with diopters:
Use the lowest power diopter that will do the job
Use  a prime lens
Use a tripod
Use a shutter release
Try not to stack the diopters
Pay attention to flare

The list could go on...

I forgot to mention, that I do most my close-up work with medium format cameras.

Here is scan of a shot a took. I violated most of my own recommendations above :-) I was stalking a pair egrets who kept me frustrated for about hour. Finally, as I walked back to the car, I realized that I was in field of flowers. I was using a Mamiya M645 with a 210mm tele. I reached into my bag and slipped on a close-up filter. The exposure f/11at 125/sec betrays my camera shake from not using a tripod.

http://www.corecomm.net/~tintype/images/corn_flower1.jpg

For a general discussion about options, try:

http://www.smu.edu/~rmonagha/mf/macro.html

Peter Mikalajunas

Photo links
http://www.megsinet.com/tintype

From: Dermot Conlan [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: FUJI GW670III -- HELP
Date: Sun, 14 May 2000

The Nikon screw in diopters work on the 69gw and 69gsw, as they are the same body as the 67 series I'm sure they will also work Here. Try www.photo.net/photo and scroll down to the "medium format digest", go to the "fuji rangefinder" section and it's asked there somewhere.

dcp

B*S*B* wrote:

> I am considering buying a GW670III via mail.  No local shops carry it.  I
> ware eyeglasses.  Will I be able to see corner to corner with my glasses on?
> Do they sell corrective lens for the eye piece?  Thanks!

Date: Wed, 21 Jun 2000
From: "John G. Silver" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Bronica PG lenses

"Rick Rieger" [email protected] wrote

> John,
>
> The Nikon 5T and 6T work extremely well on my PG lenses.  These close-up
> lenses are 62mm, so I use step down rings to attach them to my 72mm
> filter-size lenses (100mm and 150mm), and to my 82mm filter size 200mm.  I
> have not seen any vignetting of the image, even on the 200mm.  The resulting
> image quality has been very, very good.

Thanks for that Rick, I'll get some close-up lenses and will report back after testing so others can also benefit from my (our ) experiences with these lenses. I really don't want to get down the throat of something and If I did I'd probably consider a 35 mm as the best tool for that job. My 90 mm SP Tamron works fine in all respects except for producing a 6 x 7 tranny.

JS

Date: Fri, 30 Jun 2000
From: "Q.G. de Bakker" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Difference between Proxars and extension tubes

Paolo Pignatelli wrote:

>For the Hasselblad system, what is the difference in quality between
>using a proxar and an extension tube?  
>How about using them in combination?

The Proxars are optical elements added to a complex, well corrected optical system. Obviously they will incur some loss of image quality. This is true even when using Proxar lenses at subject distances that could well be covered by the lens alone, without Proxars. So don't use them when you don't really need them. If one would use Proxar lenses on Makro-Planar lenses, these beautiful lenses would indeed focus closer, but also lose their fabulous image quality. Never do this! Proxars are primarily intended to extend the focussing range just a little beyond the minimum focussing range of the lens itself. When used in this way, i.e. to achieve *very moderate* magnifications, the loss in image quality will be hardly noticeable. Loss will be more pronounced when using stronger Proxars, and/or when stacking them together. They can not be considered if you need significant magnifications (say 1:5 and more). This means that Proxars can not be used in true (regarding magnification) macro-photography, and their use is rather limited. Perhaps that's why they are being discontinued? Proxars are easier to use than extensions tubes because there is no exposure compensation (and the associated calculations) needed when using Proxars.

Extension tubes do not alter the optical system. This means that the correction of the lenses is not altered. Image quality only depends on how well the lens itself performs at the magnifications used. Obviously retrofocus design lenses, like the Distagons perform least, standard lenses like the Planars perform great, and the Makro-Planars perform even better at close range. Longer lenses, like the Sonnars, do perform very good as well at close range, but would require too much extension to achieve higher magnifications to be practical. (Though in my opinion you should always have at least the 16 mm or 32 mm extension ring at hand when using the longer lenses, just to extend their close-focussing.)

Using Proxar lenses and extension tubes together can be done. But using a lens that was designed to perform best at long range with an extension tube at close range is already putting performance under some stress. Adding Proxars might be the straw that breaks the camels' back. And, as i have mentioned before, it would be a terrible waste to combine Makro-Planars with Proxars. You will have to calculate exposure compensation based on the extension you use, not on the magnification you get.

[Ed. note: a simple trick for framing using a diopter on any camera, including non-SLR viewfinder (instamatics) or RF cameras (also much used in Scuba diving, e.g., with nikonos camera and closeup diopter lenses)]
Date: Thu, 26 Oct 2000
From: "Paul Skelcher" [email protected]
Newsgroups: rec.photo.technique.nature
Subject: Insects in flight

An interesting article in PhotoPlus this month, by Stephen Gardner.

He attached a home made-wire frame, which extended about 10", to the end of a macro lens. The end of the frame fell just outside the viewfinder, and the camera was prefocussed at that point. A bracket mounted single flash, set on TTL, or manual (set according to previous tests for mag/aperture/film speed) completed the rig.

By holding the camera at chest level, without looking through the viewfinder, he followed feeding insects and fired when he "captured" an insect within the wire frame.

In spite of the inevitable black backgounds, I thought it was a neat trick.

Paul

FRom Rollei Mailing List:
Date: Mon, 13 Nov 2000
From: J Patric Dahl�n [email protected]
Subject: [Rollei] Focus shift with Rolleinars/Proxars

I have discovered that when I focus with the close-up lenses, Proxars and Rolleinars with on my Rollei TLR's I get problems with focus shift If I use apertures around 5,6.

When I focus on the ground glass the focus is perfect on the film plane as well with the aperture fully open, but not when I stop down to 5,6. Then the focus is a little in front of the subject I focused on.

This can be a problem when you're taking closeups and want to use a large aperture to get a short depth of field.

So, I made a little "aperture", around 5,6, of a piece of black paper and put behind of the proxar on the viewing lens. Then I can focus without this problem. I made paper "apertures" for all my close up lenses, for bay I, II and III and zeiss proxars, and it works great.

Sorry for my bad english, but I hope you can understand some of it. :-)

/Patric

FRom Medium Format Mailing List:
Date: Mon, 27 Nov 2000
From: Schatzie Walton [email protected]
Reply to: [email protected]
To: [email protected]
Subject: [medium-format] Adapters, tele-extenders

AS Bob pointed out, the common perception is that tele-extenders degrade performance. This is not the case with the better made devices. In fact, at the same magnification the Rollei 2X Extender actually shows a slight improvement when used with the 150 Schneider lens (at least lpm on a USAF test chart).

The Leica ROM line of tele's all use extenders and no-one seems to complain about poor optical performance (only the price!). My Nikon and Leica extenders show no diminuition of performance, but the Vivitar (ancient) macro extender is a device to provide hours of exasperation.

From Hasselblad Mailing List;
Date: Wed, 27 Dec 2000
From: "Q.G. de Bakker" [email protected]
Subject: Re: PME-51 Diopter

[email protected] wrote:

> What is the diopter setting of the PME-51 viewfinder?  I find that most
> viewfinders are set at -1 or -0.5. I have 'over-40' disease and find that I
> need a 0 diopter for many SLR and rangefinder viewfinders, but not all.

I don't really know. But i had a problem finding a suitable lens to fit a NC2 prism i was given once. It had been fitted with a different diopter lens, useless to me. So to be able to use it myself, i needed to get the correct lens to suit my eyesight (-2.5). I had an optician measure the diopter strength of the eyepiece lens fitted, and it was +11.25 diopter! I then contacted Hasselblad and asked them what diopter strength the normal eyepiece of the NC2 was. They didn't know.

No problem though. Since i already had another NC2 finder (that i use quite happily with or without my eyeglasses) i simply took this one to the optician as well. He measured the eyepiece lens, and, lo and behold, it was +7.5 diopter.

Though i'm not sure that this +7.5 diopters is the "normal/neutral" eyepiece lens (when asked, Hasselblad said they didn't "recognize the diopter measure given as the standard one"), yet i'm pretty sure i don't need a +7.5 diopter correction lens, perhaps not all "neutral" eyepiece lenses are -1 or -0.5 diopters?

From Russian Camera Mailing List;
Date: Thu, 11 Jan 2001
From: robert svensson [email protected]
Subject: Re: Correction lenses for the Kiev 88 TTL Prism Finder?

I had the same problem. I am an old dog, 53 yrs. I am also into cheap solutions. Especially when they turn out good. Here in Sweden it is possible to buy (I have also seen them in the USA) good *PLASTIC* reading glasses for less than 4 bucks. They are available in many diopters. Since they are made of plastic, they are easy to cut to the desired shape. I just took a pair I accidentally had busted. Make a test in the store w/ your prism which strength you need. THEN buy them. Now you will have two lens elements to play with.

**One VERY important tip**: cover the surfaces w/ some good Scotch Tape in order not to scratch them during cutting or machinig/milling. Remove tape, clean the new lens and try to attach it on your finder. I did this for the K60. There was already a space for a correction lens in there.

All the best, guys

/Robert

From Hasselblad Mailing List:
Date: Thu, 25 Jan 2001
From: Henry Posner/B&H Photo-Video [email protected]
Subject: Re: Close-up Portraits

you wrote:

>Are not the Nikon two element deals only good for certain telephoto optics?

Both Nikon and Canon (who also offers dual element close up diopters) say that each is best mated to a certain focal range, but I have used both Nikons with a variety of 35mm lenses and found no significant difference.

--
regards,
Henry Posner
Director of Sales and Training
B&H Photo-Video, and Pro-Audio Inc.
http://www.bhphotovideo.com

From Rollei Mailing List:
Date: Wed, 7 Feb 2001
From: [email protected]
Subject: Re: [Rollei] TLR close-ups : prims !

> How does rollei conquer parallax w/ close-ups using diopters? Do the moving
> blades handle everything?-thx, Marcus

There is a built-in prism in the viewing lens for each rolleinar. In this case the bayonet mount is very interesting because it automatically ensures that the prism edge is actually horizontal ! This prism bends the rays downward. In theory this introduces a severe chromatic aberration but for the viewing lens and for a small prism angle this is hard to see in the viewfinder. This prism system, combined with the moving blades under the ground glass ensures a reasonable compensation for parallax at short distances within the whole range of the focusing knob for a given Rolleinar set.

When buying a used Rolleinar or a similar device (probably much cheaper ;-) made by an independent company, important things one should check is that focus is actually right (!), that viewing/taking devices have not been swapped from one set to another, and of course that the prism is not missing. These prisms have a very small angle and it may be difficult to see if they are actually there or not. I mention that because I had the problem with a cheap bayo I attachment for which viewing/taking lenses had been swapped between a 1 dioptre set and a 2 dioptre set. The mail-order shop, a very serious one, reimbursed me immediately and apologised but had not at all noticed the fault.

-- Emmanuel BIGLER [email protected]

From Hasselblad Mailing List:
Date: Thu, 25 Jan 2001
From: "Q.G. de Bakker" [email protected]
To: [email protected]
Subject: Re: Close-up Portraits

[email protected] wrote:

> Would the Nikons be as good as the Ziess Proxars?

Better. The Nikons are achromats, the Proxars aren't.

From ZICG Zeiss Interest Group
Date: Thu, 15 Feb 2001
From: [email protected]
Subject: Re: Distar

Zeiss Distars (and Zeiss Ikon Deltas) are negative diopter lenses, originally used to increase the focal length of the lens. Everything you ever wanted to know is included in "Eagle Eye of your Camera", a Zeiss publication readily and inexpensively available to Zeiss Historica members as a reprint (unless you can find an original.)

regards

Charlie Barringer

[Ed. note: Mr. Graf points out some cons of diopters vs. extenstion tubes..]
Date: Fri, 02 Mar 2001
From: GrafHe [email protected]
To: [email protected]
Subject: Diopter lenses beat extension tubes

To be honest, I am not convinced, because

a) the study where the data come from is relatively old,

b) resolution in lines per mm is not the only criterion (although others like MTF don't tell the whole truth either), just think of contrast, distortion, vignetting, etc.,

c) simple reasoning: if it were true in any case, nobody would buy extension tubes or macro lenses,

d) in the study, only a 50 mm lens with one type of diopter lens was tested, the diopters were not very high, nothing was said about the length of the extension tube, nor anything about the magnification achieved by the two, and whether they were comparable,

e) I experienced not so outstanding results with simple diopter lenses (I didn't use achromats), esp. there was significant blur in the corners,

f) comparing the price of a Nikon achromat with a Nikon extension tube, there isn't much difference,

g) I achieved very good results with the combination of a 135 or 200 mm telephoto lens and an extension tube,

h) there are many reports saying that the combination of lens A with extension tube B is good, lens C with tube D not; same could be for diopters; zooms do very often not work very well, neither with extension rings nor with diopter lenses,

i) with diopters, you add an additional lens, which costs you contrast, rendering your pictures "lackluster", and the diopter is not optimized for a special lens.

Therefore, let me add this "contra" to a lot of "pros".

With kind regards

Hermann Graf

[Ed. note: my main response would be two-fold. First, you have to use better quality 2 element achromats to get the better quality images. Second, diopters cover some ranges that commonly available tubes don't cover - so you will probably end up with diopters, tubes, and bellows to cover it all ;-) ]

rec.photo.equipment.large-format
From: [email protected] (Jess4203)
Date: Sun Mar 18 2001
[1] Re: Recommendations on Longer Lenses

Ann:

It is also possible to use a negative diopter and change your, say, 300 mm into a 640 mm with a minus two diopter (f.l.= -500 mm), but the bellow extension will be 640 mm. Blaker suggests this in his great book, Field Phtography. Stop down to at least f 11. I don't know whether the image would be degraded enough to matter.

Roy.

rec.photo.equipment.35mm
From: [email protected] (ChrisPlatt)
Date: Mon Mar 26 2001
[1] Re: Nikon FE corrective eyepiece.

Nikon SLRs are normally -1.0 with no/plain eyepiece installed. If your viewing eye is -2.0, get the -2.0 eyepiece. Nikon eyepieces are rated for the total correction when installed.

"Excelsior, you fatheads!"
-Chris-

From Minolta Mailing List;
Date: Sun, 12 Aug 2001
From: [email protected]
Subject: Re: Macro Lenses

I'm surprised that a Minolta List could forget about MINOLTA'S DUAL ELEMENT CLOSE-UP LENSES!

As good as the Nikon, of course -- and, I believe, cheaper. Come in 55mm, so they fit Minolta's excellent 100mm Macro lens. 2 strengths (3?).

I have taken some good insect photos w/Minolta non-APO 2x TC + dual-element Close-up filters (in a pinch, but it happens).

If you have the bucks for a longer Macro lens, Minolta's 200/4 Macro is right at the top, Sigma's 180 looks good for less [but no one on the list seems to have one].

Huff

To: [email protected]
From: "Parlin 44" [email protected]>
Date: Mon, 01 Oct 2001 
Subject: Re: [camera-fix] Eyepiece dioptre

Nope, I abandoned the idea, the problem is cutting/shapping the lens.  
Unless you have access to special machine optic shops use.

My solution, a bit costly ($10-15) but saves lots of trouble, is to get 
diopter eyepieces for older cameras, already cut to about the right size you 
can just simply stick it with double sided tapes on top of the view finder.

If you find a match it's a 5 min job, such as the range finder of a 6x6 
folding camera, otherwise you may need to get a little handy and creative - 
in my case I took out the lens from the frame because it couldn't fit in to 
the eye-cup, in another case for a prism of 6x6 SLR I had to unscrew the 
eyecup, place the lens inside and put the eyecup back on.

I found some old stocks of lenses for older manual nikon Fxx series.

parlin

----- Original Message -----
From: "Mark Stuart" madfamily at bigpond.com
To: [email protected]
Sent: Monday, October 01, 2001
Subject: [camera-fix] Eyepiece dioptre


 > Hi all,
 >
 > Apologies for the non-repair issue, but if I posted this on some of
 > the other photo phorums, I wouldn't get an answer I think.
 >
 > Can you make an eyepiece dioptre lens out of an old eyeglass lens
 > (plastic)?  I was thinking of finding some other device such as an
 > eyepiece rubber hood (metal framed) and attaching a cut to size lens
 > from an old pair of specs.  However, I've read that the eyepiece
 > itself has a dioptre value; for example, my Spotmatic is -1 I believe.
 >
 > Any input would be appreciated.
 >
 > Stuey
 >


To: [email protected]>
From: Bob Shell [email protected]>
Date: Mon, 01 Oct 2001 
Subject: Re: [camera-fix] Eyepiece dioptre



> From: Robert Monaghan [email protected]>
> Date: Mon, 1 Oct 2001
> To: [email protected]
> Subject: Re: [camera-fix] Eyepiece dioptre
> 
> see http://people.smu.edu/rmonagha/mf/diopter.html and mf/vision.html
> 
> if you add a diopter to the existing diopter power (glue second lens on
> etc.) then no offsets are needed; otherwise, you probably need to know
> the optical system offsets for each specific camera (they differ by model
> and brands) or have an optician check/measure them to get optimal match


The easiest thing suggested by my opthalmologist is just to take your
cameras with you to your eye doctor's office.  The all have sets of diopter
lenses that you can try out.  Just put them up to the eyepiece and look
through the camera and try to focus it. Keep trying until you find the one
that is perfect.  Then you know what is exactly right for each camera.

Worked for me and got my cameras calibrated to my eye.

Bob


To: [email protected]>
From: Bob Shell [email protected]>
Date: Tue, 02 Oct 2001 
Subject: Re: [camera-fix] Re: Eyepiece dioptre



> From: "Mark Stuart" madfamily at bigpond.com
* Date: Tue, 02 Oct 2001 
> To: [email protected]
> Subject: [camera-fix] Re: Eyepiece dioptre
> 
> I know for sure my Spotmatic F has -1 dioptry - it's in the manual.
> Mind you, I do have a touch of astigmatism - I suppose this means
> that a home made dioptre correction lens made from the correct
> spectacle lens would actually be better as it allows for astigmatism
> as well. Great! Plus, the factory ones are usually whole dioptres
> rather than, say -1.75 like mine, although I realise this is
> negligible.  


Remember two important things.  If you use a part of an eyeglass lens
and it includes astigmatism correction, you must line it up properly
when installing on the eyepiece.  Then it will be right for horizontal
or vertical shooting depending on how you install it, but not for
both.  Unless your astigmatism is bad, it is better to leave correction
for it out of lenses for your camera eyepiece.

Bob



From: "Bob Fowler" [email protected]>
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Close-up Lenses
Date: Fri, 19 Oct 2001 

"Caps990" [email protected]> wrote...
> I have a Canon Rebel 2000 and wouldlike to take some close-up pictures of
> flowers. Not looking to spend a lot of money on a real macro lenses. Does
> anyone have any opinions on close-up lenses.
>
> Thx,
>
> Gene

I carry an older Vivitar multi-coated set (+1, +2, and +4).  I can't
recommend the uncoated ones if you're not going to have complete control of
the lighting, but the multi-coated seem to work well enough.  It's no
substitute for a "real" macro lens, but you can get acceptable results if
you use some common sense like using a tripod and stopping down the lens a
little.

Essentially, by adding the positive diopter lens in front of you camera's
lens you're shortening the focal length of the total combination. I've
"cheated" in the past using a +1/2 lens on a large format lens when I needed
a little more angle of view (needless to say, the lens STILL has to have
enough covering power to pull that off).  Kodak used to make
supplementary -diopters.  I have a -1 and -2 in series VI that are REAL
handy for large format work.  They do just the opposite of the close up
lenses - used in combination with the camera's lens, they lengthen the
combined focal length.

Bob Fowler
[email protected]



Date: Wed, 09 Jan 2002 
To: [email protected]
From: Richard Knoppow [email protected]>
Subject: [Rollei] Suplementary lenses

I think I accidently deleted a post asking about calculating the focal
length of a lens with a suplimentary lens on it. 

  Suplementary lenses are usually calibrated in diopters. A diopter is the
reciprocal of the focal length is meters. So, a one diopter lens has a
focal length of one meter or 39.3 inches. + dioper lenses are postitive or
converging, - diopter lenses are negative or diverging.

 The formula for the combined focal length of two lenses is:

F = f1*f2 / f1 + f2 - d

  Where f1 and f2 are the focal lengths of the two lenses and d is the
distance between them.

  The exact focal length requires knowing the location of the principle
points but for practical use the distance can be disregarded and the
formula simplified by leaving out d. For a more exact focal length the
first principle point can be assumed to be in the space in front of the
iris diaphragm but the difference will be negligible. For practical
purposes the diopter value of combined supplimentary lenses adds linearly.

   
----
Richard Knoppow
Los Angeles, CA, USA
[email protected]


From: [email protected]
Subject: Re: [Rollei] Suplementary lenses, compound system
To: [email protected]
Date: Thu, 10 Jan 2002

 From Richard K.:

>  The formula for the combined focal length of two lenses is:
> 
> F = f1*f2 / f1 + f2 - d
> 
>   Where f1 and f2 are the focal lengths of the two lenses and d is the
> distance between them.

Hm... Richard, I am sure that you meant :

F = (f1*f2) / (f1 + f2 - d) 

this can also be written as

C= C1 + C2 - d * C1*C2   where C= 1/F ; C1=1/f1 ; C2=1/F2

when d=0 the formula is simply C= C1 + C2, the "powers" of each lenses simply add.

So assuming that f1= 100mm and if we want F=200mm and in the
simplified model of 2 thni lens elements this yields f2= -200 mm i.e.
a negative "close-up" lens of 5 dioptres.

For the most general association of any kind of thick compound lenses
another equivalent formula should be used, apparently very simple also :

F= -f1*f2/D

where D = (F'1F2) is the distance between the image focal point (F'1)
of lens #1 and (F2) the object focal point of lens #2. This may not be
easy apply except if you know exactly where the pricipal planes H1,
H'1 and H2, H'2 of the lenses are actulally located.

Assume that the additional negative lens of unknown focal length f1 is
in fact located at a distance e in front of the principal plane H2 of
the compound photographic lens. For example if f2=10cm, H2 for a
standard lens is located somewere inside the glass so e=+2cm is a
reasonable value. Then a formula identical to Richard's one is found :

F = (f1*f2) / (f1 + f2 - e) 
this eventually yields for F=20cm, f2=10cm and e=+2cm

f2=20*(2-10)/(20-10) = -16cm = -6.25 dioptres instead of -20cm when e=0

-- 
Emmanuel BIGLER         
[email protected]>


Date: Thu, 10 Jan 2002 
To: [email protected]
From: Richard Knoppow [email protected]>
Subject: Re: [Rollei] Suplementary lenses, compound system

you wrote:
> From Richard K.:
>
>>  The formula for the combined focal length of two lenses is:
>> 
>> F = f1*f2 / f1 + f2 - d
>> 
>>   Where f1 and f2 are the focal lengths of the two lenses and d is the
>> distance between them.
>
>Hm... Richard, I am sure that you meant :
>
>F = (f1*f2) / (f1 + f2 - d) 
>
>this can also be written as

  I did. I didn't think the brackets were necessary but they probably
prevent confusion.

  I wish I were better at writing algebraic stuff in ascii. 
  
  If you want to find the principle points of a lens it can be done with
simple equipment although a real optical bench is a convenience. 

  The procedure is auto-collimating. It will measure the focal length and
find the principle points.

  Mount the lens in a view camera. Make a small light source, a pencil
flashlight will do. At the simplest place a mirror over the front of the
lens. A first surface mirror is desirable but a plain shaving mirror is
good enough. Place the flashlight against the ground glass near but not at
the center. The image of the light spot will be reflected back through the
lens by the mirror. Focus for sharpest image. This gives you the exact
infinity focus point of the lens. Its a good way of setting the infinity
stops on a press cameras. 

  Now, to find the focal length focus for a 1:1 image of something. A small
ruler works well because you can place a similar small ruler on the ground
glass for comparison. The difference in bellows extension is the focal
length. Now, if the lens is returned to the infinity focus position and a
ruler used to measure off one focal length toward the lens from the ground
glass, its lens end will be exactly at the second principle point. To find
the first or front principle point turn the lens around in the mount, again
focus for infinity using the autocollimation technique and again lay off
one focal length toward the lens. You now have the focal length, both
principle points and the back focus of the lens. 

  For symmetrical or nearly symmetrical lenses the principle points will be
about one third the distance from the apexes of the lens toward the center.
i.e., if the lens barrel, or rather maximum distance from front apex to
rear apex is three inches each principle point will be about one inch in
from the front or back of the lens. 

  Of course telephoto and reverse telephoto lenses vary considerably from
this, both principle points being outside the lens. Single cells from
convertible lenses generally have one principle point, usually the one on
the convex side, lying outside the lens. 

----
Richard Knoppow
Los Angeles, CA, USA
[email protected]


From: [email protected]
Subject: Re: [Rollei] Suplementary lenses, compound system from 100 to 200
To: [email protected]
Date: Thu, 10 Jan 2002 

> Uuhm, do you say that I need a -5 lens? I'm not good at mathematics
> you see. :-) /Patric

This is easier than converting a former European national currency
into an Euro ; and yes, I know, you don't care ( --only for the moment eh,
eh...-- ) in Sweden!!

The convergence of your 100mm lens is 10 dioptres. (1 metre = 1
dioptre, 0.5metre : 2 dioptres, etc...). You want a 200mm compound
lens = 5 dioptres. So I you just have to subtract: 10 - 5 = 5
dioptres. So you need a minus 5 dioptre supplementary lens = -200mm
negative lens.

This is the meaning of C = C1+C2 : I forgot to mention that C, C1 and
C2 can be expressed in dioptres and simply add to each other with the
proper sign, + for a positive lens, - for a negative lens.

Now if your additional lens is, say, a few cms in front of the
relevant principal plane H2, actually expect 6 dioptres instead of 5
to get a final convergence of 5 dioptres for the coumpound.

-- 
Emmanuel BIGLER         
[email protected]>


From: "Dan Kalish" [email protected]>
To: [email protected]>, [email protected]>
Subject: [Rollei] Suplementary lenses
Date: Thu, 10 Jan 2002 



* Date: Wed, 09 Jan 2002 
> From: Richard Knoppow [email protected]>
> Subject: [Rollei] Suplementary lenses
> References:
>
>   I think I accidently deleted a post asking about calculating the focal
> length of a lens with a suplimentary lens on it.
>   Suplementary lenses are usually calibrated in diopters. A diopter is the
> reciprocal of the focal length is meters. So, a one diopter lens has a
> focal length of one meter or 39.3 inches. + dioper lenses are postitive or
> converging, - diopter lenses are negative or diverging.
>  The formula for the combined focal length of two lenses is:
>
> F = f1*f2 / f1 + f2 - d
>
>   Where f1 and f2 are the focal lengths of the two lenses and d is the
> distance between them.
>   The exact focal length requires knowing the location of the principle
> points but for practical use the distance can be disregarded and the
> formula simplified by leaving out d. For a more exact focal length the
> first principle point can be assumed to be in the space in front of the
> iris diaphragm but the difference will be negligible. For practical
> purposes the diopter value of combined supplimentary lenses adds linearly.

Hi, Richard:

I'm not sure what the question was but I'll supplement your analysis.  lol

If we continue to assume d=0, then the equation reduces to 1/F = 1/f1 +
1/f2, the fundamental equation of thin-lens optics.  We know the focal
length of the body lens, and the focal length of the supplementary lens is
easy to determine: either by specs or just by eye.  The result is that the
resulting overall focal length is less than either one.

The effect on aperture is to decrease the effective aperture by a factor
1/(M+1) where M is the magnification (less than 1 for reduction, greater
than 1 for magnification).  For most single or double element supplementary
lenses, this effect is negligible just as the reduction in focal length is
minor.  We can say that in general f1 >> f2.

Now, if the body lens is focused at infinity and the object is
1-supplementary-lens-focal-length away (from the supplementary lens), we've
got a very elegant model.  After the image is processed by the supplementary
lens, all rays are parallel.  To the body lens, it looks like an object at
infinity.

Dan Kalish [email protected]>
Flushing, NYC, USA



From: "Rick Rieger" [email protected]>
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Close Up Lens ?
Date: Wed, 31 Oct 2001 18:16:09 -0500

Close up lenses can be very useful and are inexpensive.  I use them with my
Bronica GS-1 and 100mm normal lens with outstanding results.  Be sure to get
the dual element lenses such as the Nikon 5T (1.5 diopters) and 6T (2.9
diopters).  The single element lenses (Tiffen, Hoya, etc.) will not perform
nearly as well.  The 5T/6T lenses are 62mm but work fine on my 100mm (72mm
filter) and 200 (82mm filter).  There is no vignetting.

"Charles Haut" [email protected]> wrote..
> I have a Kiev 88-TTL camera with only the 80 mm lens. Would a set of close
> up lens be of value or should I go to the 120 or 150 mm lens right away ?
> Thanks
> Chuck
>

From: [email protected]
To: [email protected]
Subject: RE: [Rollei] Rollei Users list digest V10 #73
Date: Thu, 29 Nov 2001 

Fredric Stein wrote:

"I am seeking information (an an example) about the Rolleinar 0.35 for the
Tele-Rollei.   Does anyone have information and /or one of these
avaialable?"

http://www.stutterheim.nl/rollei/text_pages/rolleinar_table.htm has the DoF
tables for the 0.35 with and without the more common Rolleinars.

http://www.mwclassic.com has four of them in stock, see:

http://www.mwclassic.com/acatalog/MW_Classic_Cameras_BAYONET_3___4_ACCESSORI
ES_149.html or if that doesn't work try

http://makeashorterlink.com/?O4102323

-- 
David Morton
[email protected]



From: [email protected]
Subject: Re: [Rollei] How do I use a Rolleinar?
To: [email protected]
Date: Thu, 20 Dec 2001

  From Vick:
> ...questions on the Rolleinar

> 1)  which lens goes on the viewing lens?  The long "fat" one or the
> skinny one?

The _long_ one (usually stored above the thin one as a compact stack),
goes on the _viewing_ (top) lens. Note that if the bayonet mount is
the same forboth rolleinars, the barrel has a reduced diameter so that
you can mount both lenses on the twin lens bayonets even on a 2.8 TLR
model.

> 2)  is there an "up" orientation?  

Only for the _viewing_ rolleinar lens. The reason is that the viewing
rolleinar is composed of a positive lens element of the same focal
length as the viewing one, _plus_ a prism of a very small angle, its
base being on the bottom side. Now take the viewing rolleinar, look
through it and rotate it. There is only one position for which the
image is not shifted laterally but shifted up. This is the right one.
The viewing rolleinar should be in this final position of course
_after_ turning the bayonet mount in.

> ..a red dot on the lens for the viewing lens, 

Yes the red dot is supposed to tell you where to start when attaching
the viewing rolleinar ; there are 3 positions at 120 degrees, only one
is the good one. The two "wrong" others will yield a lateral image
shift.

> ...There is a red "R" on the black rim of the long lens. There is
> also a tiny grub screw (set screw) on the fat lens that might at one
> time had red paint on it.

I should check this on my rolleinar but those details (the "R" and the
set screw) are not of any importance in normal operation.

-- 
Emmanuel BIGLER         
[email protected]>


Date: Fri, 31 Aug 2001 
From: Steven Morton [email protected]>
Subject: Re: close up lens for Noblex
To: [email protected]


Don't forget that you don't need to buy "photographic close-up" lenses
to experiment with on your Noblex.

Remember that 1000 divided by the diopter value gives you the actual
focal length of the close-up lens.
For example a 1 diopter close-up lens has a focal length of 1000mm, a 2
diopter close-up lens has a focal length of 500mm and a 0.5 diopter
close-up lens has a focal length of 2000mm

Meniscus lenses are often preferred for close up lenses but plano-convex
lenses should work well too.

Check out The Surplus Shed for cheap lenses to play with:

http://www.surplusshed.com/

http://www.surplusshed.com/list.cfm?Category=Lenses

otherwise Edmund Scientific might be worth a look

http://www.edsci.com/

Cya
Steve


From: "Herb Bauer" [email protected]>
To: [email protected]>
Subject: RE: [Rollei] rolleinars in combination
Date: Sun, 16 Sep 2001 

Actually some Rolleinars are meant to be stacked. I just checked that out
before I saw this post, and the best info is at
http://www.stutterheim.nl/rollei/text_pages/rolleinar_table.htm

Herb

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Philippe Tempel
Sent: Sunday, September 16, 2001 8:31 PM
To: [email protected]
Subject: Re: [Rollei] rolleinars in combination


No, not that I know of.  I don't think the closeup lenses are
designed to be stacked, but I never really tried.  You would
be working blindly unless you had the cut sheet film adaptor.

> Is it possible it combine various strength rolleinars to increase image
> magnification while maintaining accurate parallax compensation? If so,how?
> Thanks,
> Charlie
>


From Rollei Mailing List:
Date: Sun, 16 Sep 2001 
From: Herb Bauer [email protected]>
Subject: RE: [Rollei] rolleinars in combination

Actually some Rolleinars are meant to be stacked. I just checked that out
before I saw this post, and the best info is at
http://www.stutterheim.nl/rollei/text_pages/rolleinar_table.htm

Herb 


From nikon mf mailing list:
Date: Tue, 13 Nov 2001 
From: "Riccardo Polini" [email protected]
Subject: Re: close up filters

Achromatic (two-element) close-up lenses are preferable as far as image
quality is concerned.

Nikon produces the following achromatic lenses:

3T,  5T +1.5 diopters with 52 and 62 mm thread, respectively,
4T, 6T +2.9 diopters with 52 and 62 mm thread, respectively.

The focal length (FL, in mm) of  close-up lenses is given by 1000/D, where D
are diopters.

For example, the 5T lens has a focal length FL = 1000/1.5 = 667 mm .

Canon produces 250D and 500D achromatic lenses, whose FL is 250 and 500 mm
respectively (diopetrs are +4 and +2). Their quality is very good and are
available also with 72 and 77 mm threads.

Magnifications (or reproduction ratios, R) are easily calculated by the
following equation:

R = F/FL, where F is the focal length of the prime (or the zoom) and FL is
the focal lens of the close-up filter.

That formula holds when the prime is focused at infinity. In that case, the
working distance WD (i.e. the distance between the lens and the subject) is
equal to FL. For example, when a 200 mm is coupled to a 4T lens, 
R = 200/(1000/2.9) = 200/345 = 0.58 X = 1:1.7.

On rotating the focusing ring, magnification increases and both working and
focusing distance decrease. I calculated an empirical formula to roughly
predict the magnification at the minimum focusing distance. The formula 
is:

R(min. focus) = 1.1XR+0.1

where R is F/FL. So, one has to increase R by 10% (multiply by 1.1) and then
add 0.1.

In the case of a 200 mm lens, we get R (min. focus) = 0.74 X. Using a AIS
200/4 and a 4T lens, I measured a R value equal to 0.83 X, in good agreement
with the calculated value (which gives, as you can notice, slightly
underestimated values).

Anyway, in my web site you can find magnifications and focusing distances
attainable with Nikon achromatic lenses and many Nikkor lenses (both primes
and zooms) at:

http://space.tin.it/arte/ripolini/3T4T.htm
http://space.tin.it/arte/ripolini/5T6T.htm

Regards,

Riccardo Polini
http://space.tin.it/arte/ripolini
[email protected]



From Nikon MF Mailing List:
Date: Wed, 19 Dec 2001 
From: "Roland Vink" [email protected]
Subject: Re: Close up: lenses or extension rings?

> I know this has been discussed in various facets, so excuse me if I'm
> repeating an old theme.  What are the advantages and disadvantages of
> using lenses (types that screw in in front of the main lens) and of
> using extension rings?

== Closeup filters ==
advantages:
- small (easy to carry)
- relatively cheap
- does not affect metering
- good quality result obtained with 2-element diopters such as Nikon's 3,4,5,6T
- magnification is greater with telephotos
- easy to use - just screw on front of lens

disadvantages:
- not optimised for any particular lens
- focus range can be small, loose ability to focus to infinity
- only small increase in magnification with short lenses
- reduces working distance

== Extension tubes ==
advantages:
- large increase in magnification with short lenses
- no glass to degrade the image (third party tubes work as well as Nikon
   assuming they are mechanically sound)
- relatively cheap
- relatively small and easy to carry
- PN-11 has tripod mount
- greater working distance for same magnification


disadvantages
- small increase in magnification with telephotos (could be an advantage)
- focus range can be small, loose ability to focus to infinity
- bulkier than closeup filters
- may loose AF and metering options (some third party tubes retain these)
- extension causes light loss requiring exposure compensation if you don't have
  TTL metering or TTL flash
- fits between camera and lens so takes more time to attach

== Bellows ==
Same pros and cons as extension tubes, in addition:
advantages:
- infinitely variable extension tube
- very large extension and high magnification possible

disadvantages:
- smallest extension is quite large
- expensive
- bulky, not something to carry when hiking


== Macro lens ==
advantages
- easiest to use
- can focus from infinity to close
- most are well corrected for all distances - high quality optics
- retains all metering functions, modes, AF (depending on lens, camera..)

disadvantages
- expensive
- bigger and heavier compared to non-macro lens
- max aperture usually slower than non-macro lens

hope this helps,
Roland


From: "Leen Koper" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Portrait lens close focusing, Mamiya 7 vs others
Date: Sun, 7 Apr 2002


"Robert Monaghan" [email protected] schreef 
> I think tight head shots are a very legitimate form of shooting portraits,
> but one which can be harder or easier depending on the system used. And
> more or less costly. Extension tubes are one solution, but some systems
> charge as much as $500 and up for a simple auto-tube (others may be $75
> for a set of 4 tubes used, as with bronica s2/EC). Some systems have only
> one standard extension tube, not a broad selection.
>
> I happen to like fractional diopter closeup lenses (e.g., 1/3rd + diopter
> for Bronica 200mm but being 67mm filter, fits similar MF filter sizes,
> ~$20 used and up). see http://people.smu.edu/rmonagha/mf/diopter.html
> These add on filter like optics slightly soften the image (a plus with
> most portraits IMHO) and alter close focusing dimensions, so lens may now
> focus only closeup to 3 meters (1/3rd diopter) not to infinity, giving
> much closer focusing and much larger subject sizes on film etc. Nice part
> is you can use with different rigs, med fmt and 35mm etc.


This is probably the best way.

I always use the B&W +.25 diopter close up lens on all of my
studio portraits. IMHO cropping in camera is the only right way to do it.
Else I would use 35 mm. cameras.

Leen Koper
www.fotografieleenkoper.nl



From rollei mailing list:
Date: Tue, 26 Mar 2002 
From: [email protected]
Subject: Re: [Rollei] Do Rolleinars require exposure compensation? tricky !

> Using a supplementary lens to put you in the close-up/macro realm
> does not innately affect exposure, unlike using extension tubes or
> bellows. The explanation is a little tricky; I haven't written it up
> yet, but you can look at the discussion on this topic in the
> rec.photo.equipment.large-format newsgroup.

The idea I have about that is simply explained by the basic
photometric formula used in macro-photography:

E=pi*T*L*sin^2 (alpha')

where E is the actual exposure received in the film plane, pi=3.14..,
T is the transmission factor of the glass, including stacked filter
factors, L the luminance of the subject and and sin^2(alpha') the
*effective* numerical aperture as seen from film, where alpha' is the
angle under which the diaphragm opening is seen from film. And, OK,
this formula is non-trivial and non-intuitive but does contain
everything. Also the formula might be questionable with a very wide
angle lens like a 120 deg. view camera lens, or at high tilt angles.

If you add a supplementary lens *in front* of the main camera lens,
the only term that may vary is T (so OK if your Rolleinar is not
perfectly transparent, T will be lower) but in no case sin^2(alpha')
will vary as long as you do not alter the f-stop setting or the
lens-to-film distance. Supplementary lenses allow you to focus without
changing noticeably the lens-to-fim distance. L, the luminance of the
subject is intrinsic to the subject and is the same whether the
subject is at located at 1 inch or 1 mile. This is actually the most
mysterious thing of classical photometry, understanding the meaning of
L and how L is preserved throught an optical system. This is another
fascinating story, surprisingly related to the 2-nd principle of
thermodynamics : impossible to focus an image of the sun where the
temperature obtained at the focal point would exceed the temperature
of the sun's surface, whatever perfect the optics might be, or more
practically if you make an image of a high-temperature oven, you'll
never be able to reach a higher temperature by focusing the image of
the inside of the oven on something absorbent.

Back to Earth : the exposure factor effect is completely different
with extension tubes since sin^2(alpha') changes dramatically, as
1/D^2 when the lens-to-film distance D increases.

--
Emmanuel BIGLER
[email protected]


From: "Geoff Bryant" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Pentax close-up attachment lenses
Date: Sat, 4 May 2002


I often fit a two element diopter to a 135mm macro lens on my Pentax 67II. I
use one made for the Olympus IS series 35mm cameras (IS/L B-Macro HQ
converter) and although it is 55mm in diameter, requiring stepping rings to
fit it to the 67mm thread on the 135 Pentax, there's no vignetting and I'm
very pleased with the results.

Do bear in mind, though, the very limited depth of field of the 135mm macro
when used near 1:1. For this reason I've ordered the new 75/f2.8, which uses
the same 67mm filter thread as the 135mm, as opposed to the 82mm of the
75/4.5 lens. The new lens also focuses more closely (45cm vs 70cm).

Visit http://www.ozimages.com.au/profile.asp?MemberID=639 and follow the
links to see my images. I haven't noted which lenses were used for which
shots but it's a pretty fair bet that any real close-ups, such as the
Fittonia picture, were taken with 135+Olympus converter combination.

Geoff Bryant


"DarrenH" [email protected] wrote...
>
> Has anyone tried close-up attachment lenses on their medium-format
> equipment?  I'm interested in them for my 75mm lens because they are so
> cheap (under a hundred bucks) but I'm suspicious of the quality.  does
> anyone have an online sample or two that they might be able to show off?
>
> Thanks for your time,
> D



From: "Leen Koper" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Pentax close-up attachment lenses
Date: Sat, 4 May 2002
...

I always use a B+W  +.25 close up lens on my 150 mm to be able to move in a
little closer in studio portraiture. When I 'm doing pack shots (for
catalogues etc.) of relatively small objects I use a B+W +2 lens.

Leen Koper
www.fotografieleenkoper.nl



Newsgroups: rec.photo.equipment.medium-format
Subject: Re: wide angle folder?
From: [email protected]
Date: Wed, 15 May 2002

 >  Should have remembered the problem from fitting
 > wides and telephotos to my graflex.

BTW, it is possible to get a wider view on a bellows camera with GG back by
simply using a +1 or +2 diopter and refocusing.

John



From: "Rick Rieger" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Pentax close-up attachment lenses
Date: Thu, 9 May 2002


I use the Nikon 5T/6T two element diopters on a variety of lenses, including
100mm and 200mm lenses on a Bronica GS-1.  The results are outstanding.  I
don't have any to show right now (no scanner yet).  No vingnetting, even on
the PG 200mm with 82mm filter thread.

Rick R.

"DarrenH" [email protected] wrote
>
> Has anyone tried close-up attachment lenses on their medium-format
> equipment?  I'm interested in them for my 75mm lens because they are so
> cheap (under a hundred bucks) but I'm suspicious of the quality.  does
> anyone have an online sample or two that they might be able to show off?
>
> Thanks for your time,
> D



From: "Eric Stral" [email protected]
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Pentax close-up attachment lenses
Date: Sun, 12 May 2002


I also use the Nikon 5t/6t lenses on my Pentax 645 lenses with outstanding
results.  I have scanned these images and find no problems.  Note: I am
using the 62mm Nikon accessories on 58 mm thread Pentax lenses, thereby
using the "sweet spot" of the accessories.

Eric


"Rick Rieger" [email protected] wrote 
> I use the Nikon 5T/6T two element diopters on a variety of lenses, including
> 100mm and 200mm lenses on a Bronica GS-1.  The results are outstanding.  I
> don't have any to show right now (no scanner yet).  No vingnetting, even on
> the PG 200mm with 82mm filter thread.




[Ed. note: thanks to Anthony Skirlick for sharing this tip on diopter swapouts!]
Date: Tue, 21 May 2002 
From: Anthony Skirlick [email protected]
To: [email protected]
Subject: (no subject)

this may be of help for you....I was searching all over the place to
solve my diopter problem with my Mamiya 645 1000s CDS prism finder.
There are no dipopters available it seems except the big screw in one
for the waist level finder.  Anyway this might help.  I have several
NIKON SLR's and I found that diopters that fit over the view finder for
the F/401, 401x, F601/F501 etc fit exactly the CDS prism finder!!!  It
is a perfect fit.  I use the 2+ diopter and the serial number for the
Nikon product (skew)  18208  02943 3..and it has Nikon F-501 on the
small gold box it came in..  This is available through B&H.  There are
of course other diopter formulations available with this mount.
Secondly....the rubber eye piece that would normally hold the Mamiya CDS

prism finder screw in diopters (which I cannot find to save my life)
will NOT fit the outside of the Nikon diopters once mounted on the prism
finder but it appears that with a bit of tweaking with needle nose
pliers you might be able to spread the flanges on either side enough to
fit over the Nikon diopter lens.

But what I also found out is that the round NIKON diopters that are used
on the  FA, FE2, FM2 (which coincidentally is the the SAME round diopter
that fits all the F2 finders)  will insert perfectly into the Mamiya
eyecup but will not thread since it is just barely not wide
enough...however with just a spot or two of super glue...it will stay
perfectly in place inside the eyecup.  You then could not tell whether
this was a Mamiya or some other brand of diopter once it is inside the
eyecup with a nearly perfect...the skew number on my 2+  Nikon
FA-FE2-FM2-FE-FM diopter is 18208 02933 4...and is available through
B&H.

 If you have any questions about this, please let me know...but this
certainly had become a problem for me since I do not like using eye
glasses and would always rather use diopters.  Tinkering around this
morning with these Nikon diopters solved the problem.  I tried so many
stores and both new and used to obtain diopter correctors for the CDS
prism and was told NOT AVAILABLE or we NEVER get them....etc..that I was

wondering if Mamiya EVER produced them in the first place!!!!!  This is
a doable and cheap work around...and cosmetically nearly a perfect
solution.



[Ed. note: thanks to Anthony Skirlick for sharing these diopter swapping tips again!]
Date: Tue, 21 May 2002 
From: Anthony Skirlick [email protected]
To: "Robert Monaghan Medium format fit...." [email protected]
Subject: [Fwd: (no subject)]

Robert...

since you do medium format....along with Yashica Mats, RB67's, M645's,
Holgas (toy) , but I also own some Kiev stuff which you guys probably
don't even consider cameras since you appear to be a high end type of
outfit...but just in case....I forwarded this to Mike Fourman (who is a
nice guy)  a while ago today  since the circular Nikon diopter is like
aspirin at this point in solving many diopter problems along with the
more traditional rectangular Nikon one I mentioned..  Anyway the Kiev
88cm metered view finder along with all the other Kiev products do not
have diopters in the United States even though all current Kiev cameras
are machined for them...but it looks like all the dealers don't want to
aggressively track them down and import them.

Diopter adjustment IS a big deal and as you mentioned when the baby
boomers me included reached our 40th birthdays, we all went semi-blind
en mass..

Anyway...this little discovery here was just as important as my M645
discovery...all taking place within an hour...like I said these Nikon
diopter are the cure all...like aspirin....more and more uses are
cropping up with them!!!!!!


Hope you can use this post too!!!  The Kiev 88cm prism finder is really
pretty neat BUT there was NO diopter available....my work around here
was as if it was a near custom fit for the Kiev....REAL SIMPLE!!!

I am sure there will be hype purists out there who might discount my
suggestions but you might want to try these out yourself..!!!!

Anthony Skirlick
-----
Date: Tue, 21 May 2002 
From: Anthony Skirlick [email protected]
To: Michael Fourman [email protected]
Cc: "John C. Valverde" [email protected]
Subject: (no subject)

Michael,

Good news...I discovered something that may assist you in regards to
diopter corrections on some of the Kiev's..


On the Kiev 88 PDS eye level prism  finder I found that  a Nikon diopter
fits!!!!...Simply unscrew the eye piece and insert a Nikon diopter
(various formulations are available) . Once it is inside and placed into
the hole it is nearly a perfect fit...then you simply screw back on the
eye piece/rubber eye cup and the whole thing stays firmly in place!!!
There is no machining or doing anything else...IT WORKS.....the skew
number on my 2+  Nikon FA-FE2-FM2-FE-FM diopter is 18208 02933 4...and is 
available through B&H  (this SAME model fits all Nikon F2 prism finders by-the-way).  
It is made of metal and is round and is very sturdy.  I tested close
focusing on written material with my glasses on and this diopter
arrangement and it is the same focus as my glasses...exactly the same.
It seats perfectly into the Kiev metered prism finder!!!

This same diopter can be placed in the eye level finder of the Kiev 60
with super glue around the edges and works fine as a diopter
adustment...you simply glue it to the front piece where your eye would
look....this round Nikon diopter will not seat inside the viewfinder
with the eyepiece screwed back over it and locking it in place like the
Kiev 88 finder.  With some machining, I guess you could do it..


I am sure this information ESPECIALLY on the Kiev 88 is very important
and you might order this yourself from a local camera store if you did
not want to go through B&H and check it out yourself.  It works.  Then
you could offer it from your own company and I am sure your
customers would appreciate it.  I have not seen this posted anywhere
by-the-way...  I could not believe the answer had been here all
along....

The seating of this round metal Nikon diopter on the Kiev 88 eye level
spot meter finder that comes with the package is perfect...no vignetting
or anything once it is inside and the resecured by screwing back on the
eyecup rubber/metal part!!  And like I said...every imaginable
formulation of diopters is available!!!!

Hope this helps you, Mike!!

I am still awaiting your availability of the 220 back for the Kiev 88
and if you have any used 120 mm P lenses..

Also...have you ever heard of anybody using 220 on the Kiev 60????

Cordially,

Anthony Skirlick
Valencia, CA.


From: [email protected] (Mark Roberts)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Pentax close-up lens question
Date: 12 Jun 2002 



DarrenH wrote:

> Hello all,
> Regarding the Pentax close-up lenses S56 and S33:  What do the numbers
> denote?  Degree of magnification?
>
> The product numbers at B&H are PECULS33645 and PECULS56645.

Pentax has 5 close-up lenses as far as I know: S33, S56, S82, T132 and
T226

>From http://www.angelfire.com/ca/erker/closeups.html:

"Pentax CU lens names are S or T followed by the lens focal length in
centimetres. The S means that the CU lens is designed for a short
focal length lens, generally the normal lens for that format (50mm in
35mm format, 75 mm in 645 format etc). The T stands for Telephoto and
thus are meant to be used with telephoto lenses in that format (80mm
and up in 35mm format etc). To convert the cm focal length into
diopters divide 100 by the cm (eg. the T33 is 100/33= 3 diopters)."

BTW: I've use the now-discontinued Sigma 2-element (achromatic)
multicoated close-up lens with good results. It's a 58mm thread and
about 1.6 diopters.



From: "David Harper" [email protected]
Newsgroups: rec.photo.equipment.large-format
Subject: Telar and Portra lens
Date: Thu, 01 Aug 2002


Hi,

Just found a set of Kodak Porta lens (diopters +1,+2,+3) that when used with
ground glass backed cameras modify the focal length as if a wide angle lens
were being used.  Haven't gotten any film back yet, but....

Has anyone out there used them, if so, what were your results???

Also, I understand that a set of negative diopters (called either Telek,
distar, or Telar) were also made. That creates a telephoto effect.

Does anyone know where I can find a set of the Telek/Telar/distar lens.  I'm
trying to set up a 6x9 field camera to keep with me on the road.  I figure
on using my prime for most things, but I figure using these stopped down,
will give me greater flexiblity and use less space than trying to carry 3 or
4 lenses everywhere.

If someone reading this has a set they want to sell for a decent price, or
can point me in the right direction please email me directly:
[email protected]
and we can work out the details.


Thanks in advance.

David



From: Louis Boyd [email protected]
Newsgroups: sci.optics
Subject: Re: Magnifying glasses.
Date: Thu, 25 Jul 2002


"H.N.Rutt" wrote:
>
> Now here is a nice classical optics question for sci.optics :-)
>
> If I buy a magnifying glass, its says it is x3,  x5,  x20, whatever.
>
> But it is just a lens of given focal length. I can use it at any conjugates
> I like & get any magnification I like, within practical limits.
>
> So what is the assumption built in when they specify it as x3 or whatever?
> Is there some aspect of how we 'naturally' use a magnifying glass which will
> lead me automatically to use a particular focal length as an x3 magnifier?
> I rather suspect the eye may accomodate to its nearest distance of clear
> vision when using a magnifier........but that still doesnt seem to imply
> that a particular focal length lens gives a particular magnification.
> Whast am I missing?
>
> Harvey


The part missing is how far the lens is from the object when in use
relative to a comfortable minimum viewing distance without the lens for
a person with normal eyesight.

I believe the standard definition of magnification for a single lens
used as a visual magnifier assumes that distance to be 1/4 meter so the
relationship of focal length to magnification and is given by:

M= 1+(250/f)  (where f is the focal length in millimeteres)

The only referenc I've found on the web is:
http://www.ruf.rice.edu/~dodds/Files231/expt05.pdf
page 4 equation (5-6)

That seems to agree with what I see for the magnifications vs focal
lengths advertised by various manufactures of loupes and hand
magnifiers.

--
Lou Boyd
Fairborn Observatory


From: Repeating Decimal [email protected]
Newsgroups: sci.optics
Date: Thu, 25 Jul 2002
Subject: Re: Magnifying glasses.

...(quotes above query)

This is explained in Born and Wolf in Section 6.6 which is on p251 of my
edition. The image of the object is placed at 25 cm from the eye, the near
point. Distances shorter than this cannot be acommodated. Good practice
would place the image farther away than at the near point so as not to cause
eystrain, perhaps at infinity. That change does not affect the angular
subtense by much. The magnification is approximately 25/f where f is the
focal length in cm.

Bill


From rollei mailing list:
Date: Sun, 7 Jul 2002 
From: Jonathan Prescott [email protected]
Subject: [Rollei] Rolleinar sample shots

Douglas was asking about the quality of Rolleinars, so I thought you all
might like to see a couple of shots I took of my daughter yesterday
using a 2.8C Xenotar with rolleinars.  Both images are on Delta 400 in
Xtol, printed on Ilford MGIV and scanned.

http://prescottphoto.com/images/sew2.jpg
        Rolleinar 1, f8, 1/50th, handheld

http://prescottphoto.com/images/sew3.jpg
        Rolleinar 2, f11, 1/50th, handheld

I'm quite happy with the quality of the rolleinars, which in the case of
these pictures means that the eyes are rendered sharply.  But it's easy
to let near objects loom excessively when using rolleinar 2's.

Jonathan Prescott


From rollei mailing list:
Date: Mon, 08 Jul 2002 
From: Jerry Lehrer [email protected]
Subject: Re: [Rollei] Rolleinar sample shots

Doug

On the contrary, flare has never been a problem with Rolleinars
if they are coated and ALWAYS used with a lens hood.  The use
of third party close-up lenses has usually been the problem.  They
also are not as closely matched in diopter as the F&H Rolleinars.

I have found only one close-up diopter lens that is of better quality
than the F&H; and that is the Nikon 5T and 6T but those cannot be
used with Rollei TLRs.  I use them with my Hasselblad as well as
my Nikon.  I wager that they can be adapted to the SLR Rolleis
that take 6x6cm.  They are much superior to the Zeiss Proxars that
I had been using on my H'blad.  One would need an adapter ring
that steps up/down to 62mm size.

This has been the subject on the Medium Format Digest which
has been the source of a lot of useful information.

Jerry Lehrer


From: "Olaf Ulrich" [email protected]
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Close up filters ?
Date: Mon, 5 Aug 2002


Joseph Kewfi wrote:
> Do close up filters (magnifying)
> create distortion?

Usually, they don't---except when they are low quality.
Actually, high-quality close-up lenses can *reduce*
distortion!  This can happen with highly asymmetrical
base lenses.  These can be more or less distortion-free
at infinity but show significant distortion at close
distances.  With a high-quality close-up lens, the base
lens can be left at or near infinity where it performs
best.


Joseph further wrote:
> Any suggestions on which brand
> to go for?

Depends on your lenses.  Which lenses (focal length,
filter thread diameter, minimum focusing distances)
are you planning to use the close-up lenses with?


Q. G. de Bakker wrote:
> Just make sure they are achromatic
> doublets, and not just single lenses.

Those achromatic doublets indeed are the best kind of
close-up lenses.  But neither are they available in all
sizes and strengths nor are they always actually needed.
If the close-up lens' focal length is at least approx. ten
times the base lens' focal length then you may just as
well use a single-element close-up lens.  Stronger close-
up lenses however, for larger magnifications, indeed
should be of the achromatic kind.

Olaf



From: [email protected] (Neuman - Ruether)
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Close up filters ?
Date: Mon, 05 Aug 2002

"Joseph Kewfi" [email protected] wrote:

>> Depends on your lenses.  Which lenses (focal length,
>> filter thread diameter, minimum focusing distances)
>> are you planning to use the close-up lenses with?

>I was thinking of using them with my Nikon 50mm 1.8D lens which is 52mm
>filter size.
>I don't have a specific use for them, I thought I might experiment with
>close up filters and not spend too much cash on them as I've never used them
>before and don't know what to expect , I can't tell how much use they might
>get.

The results can be sharp (stopped down at least some,
but the lens-system front-to-focused-subject distance
can be VERY small, making it awkward to shoot without
casting an inappropriate shadow (close-up lenses work
by shortening the FL of the lens [without shortening
the barrel length], effectively making the combination
into a shorter FL lens on tubes...).

David Ruether
 [email protected]
 http://www.ferrario.com/ruether


From: "Olaf Ulrich" [email protected]
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Close up filters ?
Date: Tue, 6 Aug 2002


Joseph Kewfi wrote:
> > > Any suggestions on which brand
> > > to go for?
> >
> > Depends on your lenses.  Which lenses
> > (focal length, filter thread diameter,
> > minimum focusing distances) are you
> > planning to use the close-up lenses with?
>
> I was thinking of using them with my Nikon
> 50mm 1.8D lens which is 52mm filter size.

Well---Canon, Leica, Minolta, and Nikon all make decent two-element
achromatic close-up lenses. You should go for those made by Nikon
because they are the right screw-in size for you: 52 mm.  The best
strength for a standard lens would be +2 dpt.

Nikon offers two achromatic close-up lenses in 52 mm size and two
in 62 mm size.  They are pretty expensive when bought new but they
show up from time to time on eBay and go for approx. half their
retail prices, sometimes even less.

You may also buy a Minolta Close-up Lens No. 1 which also has
the required strength of +2 dpt but is 55 mm in diameter.  So you'd
need an additional 52->55 mm filter adaptor ring.  A looong time
ago Minolta also offered their close-up lenses in 52 mm size but
those are extremely rare today.

I don't know the strengths and sizes of the other brands' products.
But if they fit your needs you may buy any of them since they all
are high quality.

The close-up lenses offered by the common filter manufacturers, like
e. g. B+W, Heliopan, Hoya, Tiffen usually are non-achromatic single-
element lenses.  The occasional exception to this rule exists.

Olaf


From manual minolta mailing list:
Date: Sat, 7 Sep 2002
From: [email protected]
Subject: Re: close up lens sets?

 [email protected] writes:

 They come in sets...1, 2 and 4 usually. 

Minolta's are 0,1 and 2, but they are about the same as the normal 1, 2 and 4.


From: [email protected] (ArtKramr)
Newsgroups: rec.photo.equipment.medium-format
Date: 03 Sep 2002 
Subject: Re: Rolleinar (TLR) parallax questiion

>When using rolleinars for close-up work I find that my compositions are not
>accurate to what I see and compose on the ground glass.
>I have the newer 2 part rolleinar set with the 'larger' piece for the
>viewing lens supposedly correcting parallax and the smaller piece for the
>taking lens..
>Am I missing something ?
>
>thanks
>Frank


When you use your Rollienars is the red dot up?

Arthur Kramer
Visit my WW II B-26 website at:
http://www.coastcomp.com/artkramer



From zeiss interest group

Date: Sun, 6 Oct 2002 
From: [email protected]
Subject: Re: What is  Zeiss DISTAR ?

Just to complete the answer from Bill, which is 100% correct ...
Proxars and Distars were developed in the time of plate cameras focused on
groundglass and served as, respectively, a (modest) wide angle add-on and a
(modest) "telephoto" add-on to your basic camera lens. Their effect could be
judged only on groundglass, and required the ability to contract or extend
the bellows to reach infinity focus with the new focal lengths.
The use of the Proxar as a closeup lens came afterward. Obviously, the
analagous use of the Distar is nonsensical.

See the Zeiss Historica Society reprint of "The Eagle Eye of your Camera,"
available to members, for a more complete discussion.

Charlie

Martin Tai wrote:

>   Zeiss Proxar is  close up lens
>   What is Distar ? Is this tele attachment ?  or  wide angle
> attachment ( distagon )
>
> martin
>

Martin, I'm sure you know what a Proxar is; it's a positive
lens, used as an auxiliary to a camera lens, to reduce its
focal length.

A Distar is exactly the reverse. It is a negative lens, used
as an auxiliary to a camera lens, to increase its focal length.

Bill Lurie



From minolta mailing list:
Date: Fri, 25 Oct 2002 
From: "Maisch, Manfred" [email protected]
Subject: Minolta close up diopter

Hi,
waiting nearly 2 months after ordering I received a Minolta close-up diopter
No. 0 (0,94 dioptrin) yesterday. I bought it mainly for my 4/70-210mm lens,
to improve it's macro capability when I want to hike with a lightweight bag
and don't take a separate macro lens with me. I'll tell you about my
experiences.

It was interesting to look at the description inside the package about the
Minolta diopters:

*       "No.0 is designed for standard lenses but can also be used with
telephoto lenses up to 200mm focal length

*       No.1 is designed for standard lenses but can also be used with
wideangle lenses down to 24mm or  telephoto lenses up to 200mm focal length

*       No.2 is designed for standard lenses but can also be used with
wideangle lenses down to 24mm focal length"

So my No.0 will be well suited for my 4/70-210mm, but at the far limit of
usability at the long end. And I was not aware of this limitation, when I
bought it (lucky me, that I didn't order the No. 2 diopter).
Yesterday evening I took a short look at the diopter chapter of Jhon Shaws
"Close Ups in Nature"  and found, that as far as he knows, only the Nikon
diopterd are designed for tele lenses.

Manfred



Date: Tue, 03 Dec 2002 
From: [email protected]
To: [email protected]
Subject: Re: [HUG] Proxar

Tom Christiansen [email protected] said:

>Folks,

>I'm thinking of getting myself a Proxar close-up filter. The only sources
> in the US I've been able to identify are KEH and Glazer's Camera in
>Seattle. Not that there's anything wrong with either, but does any of you
> know of another source? It's nice with a little selection to choose
>from...

>Another thing. I understand that they come in three different "focal
>lenghs"; 2.0, 1.0, and 0.5 meter. What exactly does this mean? Is this
>the  focusing distance when the lens the Proxar is attached to is focused
>on  infinity focus? If so, how do I calculate the focusing distance when
>the  lens is focused on minimum focus?

>And last... Does anyone have practical experience with one or more of
>these  Proxars? Good/bad? Is one lens better with a Proxar than another?


>Thanks,
>
>       Tom

Proxars are single lens optics mounted in the equivalents of filter
mounts, to be used as suplementary lenses in front of the camera lens. The
Proxar 0,5 ha s a focal lengrh of 0,5 meters, wich means that an object
placed 0,5m in front of the Proxar will be rendered sharp on the film,
when the camera lens is set to infinity. These lenses introduce some
optical errors when placed in front of the well corected camara lens. To
ensure sufficient quality the camara lens should be stopped down 2 or 3
stops (Or you will see unsharpness and softness in the corners of the
picture, this is even more pronounced when using a long foval length as
camera lens.) I have and use the Proxar 0,5. I used only with the 80 mm
Planar, and when I photograph say a document in the size of DIN A4, I get
quite acceptable results with the lens set at f11 or f16. Of course I know
nothing of supliers in the US, but if you use CF or newer lenses, any
Hasselblad dealer would be able to supply you. If you use C lenses yoy
would have to find them second-hand.

Regards

John Dancke




Date: Wed, 12 Feb 2003 
From: Tom Christiansen [email protected]
To: [email protected]
Subject: [HUG] "Test" results: Nikon close-up lenses on 80CB and 150C.

Folks,

I got some 2-element Nikon 5T and 6T (62mm, +1.5 and +2.9 diopter
respectively) in the mail the other day. I tested them on my 80mm CB (with
a B-60 to 62mm step-down ring) and on a 150mm C (with B-50 to 62mm
electrical tape (poor man's step-up ring)).

Those diopters are actually fairly impressive. The only thing that annoys
me is that the focusing range is rather limited once you stick the diopter
on the lens. I've used a few macro lenses and they've all focused from
infinity to 1:1 at the twist of a lens barrel, thus, giving a lot of
freedom in composition. With the diopter, you get close in a hurry - which,
I suppose, is also the point... Anyway.


I shot with 80CB + 6T; 80CB + 5T; 80CB + 6T + 5T; 150C + 6T; 150C + 5T; and
150C + 6T + 5T. When stacking diopters, I followed Nikon's advice and put
the diopter of lowest power (the 5T) furthest away from the lens.
I shot at apertures in the range of f/4 to f/32 shooting at least three
pictures (at different f-stops) of the same subject.

RESULTS
1) It's true!! You really don't need to apply exposure compensation or
bellows extension when using diopters.
2) The DOF is incredibly shallow with both diopters on the lens!!
3) I notice no vignetting and no significant light fall-off with any of the
combinations or at any of the tested f-stops.
4) Sharpness/resolution/contrast: I'm sure my Contax Makro Apo-Planar could
do better, but it doesn't fit on the Hasselblad mount... I'm also sure that
the 'blad macro lens would do better, but it doesn't fit in my shirt
pocket... That being said, I'm rather impressed with the sharpness of these
diopters. Granted, they don't outperform the real macro lenses, but they
are actually reasonably close. I think they are an incredible deal at $40
each!! On the flower shots I did, you can definitely tell the minute
details, lines/veins in leaves, "hair", etc.

I've tossed some pictures up on my website. I was kinda in a rush to get
these pictures so I didn't spend too much time finding the right subject
and such. I just wanted to get a rough idea of the performance of these
close-up diopters.

150C lens with 6T diopter (f/16, 1/15 sec):
http://students.washington.edu/tomchr/pictures/Winter2003/150C6T.jpg  (full
frame)
http://students.washington.edu/tomchr/pictures/Winter2003/150C6T-Detail.jpg
(detail)

150C lens with 6T + 5T diopters (f/11, 1/30 sec):
http://students.washington.edu/tomchr/pictures/Winter2003/150C6T5T.jpg
(full frame)
http://students.washington.edu/tomchr/pictures/Winter2003/150C6T5T-Detail.jpg
(detail)

Tom



From minolta mailing list:
Date: Thu, 6 Mar 2003 
From: Ulrich Olaf [email protected]
Subject: Re: Diopters

Ken "red93miata" wrote:
> I will look forward to reading a
> technical explanation (Olaf?) ...

Okay okay ...

The camera's eye-piece is set to -1 dpt which
means that the image on the viewfinder's ground
glass---which really is approx. 1" away from the
eye-piece---appears to the normal-sighted person
at a virtual distance of 1 m (3' 3 3/8").

To the near-sighted person, it appears at a
greater virtual distance; to the far-sighted it
appears to be closer.

Put yourself in front of your computer monitor so
the distance between your eyes and the screen's sur-
face is 1 m (a few inches to or fro don't matter).
Take off your glasses and look at the screen. Can
you read all text sharp and clear? Then you can
focus an SLR camera also. If your near- or far-
sightedness is so strong that you cannot sharply
see an object 1 m away without glasses then you
must either wear your glasses while focusing, or
use an eye-piece correction lens (but not both, of
course).

If the strength of your glasses is somewhere bet-
ween -1 dpt and +1 dpt then you can still use
the camera without glasses, usually. If your
glasses are stronger than that, either positive
or negative, then action must be taken in one way
or another. Some prefer simply wearing their
ordinary glasses, some wear contact lenses, some
use eye-piece correction lenses.

It is not possible for any kind of ametropy to
falsely see a sharp image on the focusing screen
when it really is off focus. Instead, the sharp
image on the screen will appear unsharp, and the
mis-focused image will appear even more unsharp.


Regards,
Olaf
--
Olaf Ulrich, Erlangen (Germany)
[email protected]


From minolta mailing list:
Date: Thu, 06 Mar 2003 
From: William Morris [email protected]
Subject: Re: Re: Diopters

Just a note: camera designers make different optical choices so a
corrective lens from one make of camera will probably not work well on
another. A quick way to find out is to remove the lens from the camera
and then look through the view finder at a bright white wall then
experiment with different corrective lens until the grain of the focus
screen is the sharpest. 

Bill
...


From: Bill Pearce [[email protected]] 
Sent: Mon 3/17/2003 
To: [email protected]  
Subject: [HUG] eyepiece glue

Tom,

I suggest you try Pliobond. Here, it is stocked at Ace hardware stores. A
similar glue is Walther's Goo, sold at hobby stores. It is a rubber based
contact cement. the eyepiece will be removable, but will stay on in most
situations, and the glue residue should be removable, too. It does not loose
it's bonding power with time, like rubber cement.

Best not to apply to eyepiece and eye, however,

Bill Pearce



From hasselblad mailing list:
From: Tom Christiansen [[email protected]] 
Sent: Thu 3/27/2003
To: [email protected] 
Subject: [HUG] TEST RESULTS: Proxars vs Nikon 5T, 6T

Folks,

Jim Brick kindly lend me a couple of Proxar diopters and I shot some film
with them and my Nikon 5T and 6T diopters.

The contestants: Zeiss 0.5m Proxar (+2 diopter), Zeiss 1m Proxar (+1
diopter), Nikon 5T (+1.5 diopter), Nikon 6T (+2.9 diopter).

Conclusion: The two-element Nikon designs outperforms the Zeiss Proxars
both with respect to sharpness/contrast and chromatic aberrations. The
difference is quite significant as shown in examples referenced below.
However, in a "real world" type application (product photo - not shown),
the Proxars and the Nikons are reasonably close. Still the pictures with
the Nikon diopters are just a tad snappier. I guess Zeiss would rather sell
macro lenses than diopters...

Initial impressions: The Nikon diopters are actually quite heavy. I'd
expected them to weigh the same as a filter but they are significantly
heavier. The Proxars on the other hand, are quite light and I suspect that
the lens is made out of plastic/polycarbonate. The proxars offer the
significant advantage that they fit the Hasselblad bayonet filter ring as
opposed to the Nikon's 62x0.5mm filter thread. I had trouble focusing with
the Proxars. The chromatic aberrations of the Proxars combined with the
split-screen and WLF magnifier was so severe that I couldn't focus using
the split-screen. Had to focus on the ground glass. No problems focusing
with the Nikon lenses.

Tests: Sharpness test was done with the classical "newspaper stock quotes"
test. Chromatic aberrations were tested using a high-contrast, laserprinted
test subject (some large X'es on paper).

I shot with the 180mm CFi at f/4 and f/16. All conclusions are drawn from
the images shot at f/16. And, yes. Of course I used tripod, MLU, cable
release. I also tried the diopters on the 60mm CF just for kicks.

Sharpness/Contrast:
1) Nikon 5T
2) Proxar 1m
3) Proxar 0.5m
For some reason I didn't test the 6T...
All the diopters are rather close in performance when it comes to
sharpness/contrast in a rather low-contrast situation (newspaper in soft
light). Only on the 60mm CF was there a SIGNIFICANT difference between the
Nikons and the Proxars. The latter being incredibly soft in the corners. I
observed no vignetting with either brand of diopters.

Chromatic aberrations:
See examples: http://students.washington.edu/tomchr/pictures/ProxarTest/
1) Nikon 5T
2) Nikon 6T
3) Proxar 1m or Nikon 5T, 6T stacked
4) Proxar 0.5m
5) Proxar 0.5m, 1m stacked

The general tendency is that the higher diopter power, the more aberrations
- which is expected. The two Nikon diopters perform almost equally well. As
do the two Proxars. But expect "severe" image degradation if you stack the
diopters.

Happy shooting. And thanks Jim for the loan of Proxars.


Tom


From hasselblad mailing list:
From: Tom Christiansen [[email protected]] 
Sent: Sat 3/29/2003  
To: [email protected] 
Subject: [HUG] Proxar test results elaboration, addition


Folks,

I've put some "real life" Proxar/Nikon pictures on-line. Have a look-see:
http://students.washington.edu/tomchr/pictures/ProxarTest/

Maybe I wasn't clear in my initial email, so I thought I'd elaborate a bit
on how I came up with the test.

I wanted to test the 1-element design of the Proxar vs the 2-element design
of the Nikon. When changing from a 1-element to a 2-element design, one
would expect less chromatic aberrations from the 2-element design.
Increasing aberrations can be perceived as an over-all loss of sharpness.
And upon inspection of a high contrast "step" in luminance, the aberrations
can be seen as color fringes along the "step".

So I tested sharpness/contrast, chromatic aberrations, and made one "real
life" shot (product shot).

The conclusion is still: The 2-element Nikon designs are significantly
better than the 1-element Proxar design when it comes to chromatic
aberrations. And the 2-element designs are a noticeably sharper than the
1-element designs. The same tendency was shown in the "real life" product
shot. The image taken through the Proxar was noticeably softer than the
image taken with the Nikon diopters. With the Nikons I could clearly make
out the duo-tone of the print on the product packaging. With the Proxars
the duo-tones were almost smeared into a solid color.

As much as I love the Zeiss lenses, I must admit that this time, the Nikons
win hands down.


Tom


From nikon MF Mailing List:
Date: Mon, 28 Apr 2003 
From: "Roland Vink" [email protected]
Subject: Re: Close up lenses

> Although I have a 55 mm f3.5 micro, I have been
> thinking of getting close up lenses to use on my 105
> f2.5 and 200 f4. I'm not sure whether to get a 3T
> and/or 4T or to get the close up lens set (#0, #1,
> #2). The set is cheaper than the 3T and 4T combined
> but am not sure which will give me the greater
> magnification and/or sharpness with the lenses
> mentioned.

Hi Steve,
The 3T and 4T are two element closeup filters, the are better
corrected than the single element #0, #1 and #2 filters.

The 3T has a diopter of 1.5 so the focal length is 1000/1.5 = 670mm.
This is also how far in front of the lens it will be focused. The
magnification with your 200/4 lens focused at infinity is 670/200 =
1:3.3, a little greater with the lens focused close.

The 4T has a diopter of 2.9, focal length is 1000/2.9 = 340mm. The
magnification with your 200/4 is 340/200 = 1:1.7.

Either the 3T or 4T will give you a rather restricted range of
magnification, it really depends on how much magnification you want.


From camera fix mailing list:
Date: Wed, 23 Jul 2003 
From: "Roger Provins" [email protected]
Subject: Re: Corrective eyepieces

For several years I have bought cheap "reading" glasses from markets for a
pound or two (in the UK) and cut from the plastic lenses a piece to exactly
fit into the eyepiece of the camera. Depending on the type camera these can
usually be made a "snap" fit and will stay securely in place yet be easily
removable. Rectangular ones are easily and quickly made with a fine saw and
a miniature file. Circular ones are a little more demanding. I've fitted
these to most of my small collection of early SLRs and rangefinders. In the
few cases where it has not been possible to fit the correction lens within
the eyepiece I've found or made up a short tube to fit over the eyepiece
surround and fitted my lens in that.



Roger

Gloucester



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