Precision Camera and Lens Repair
Email PCL
John Van Stelten
1017 S. Boulder Rd.
Suite E-2
Louisville, CO 80027
Ph: 303-665-6640
Fax:303-665-3803
EMAIL: [email protected]
Paul Ebel
W230 Terrace St. POB 86
Spring Valley, WI 54767
715-778-4372
Lens Services:
medium format lenses, cameras - CLA $58
view lens CLA $36
speed recalibrations $16
recement view lens elements $55
Rangefinder adjustments $45
brilliant focus screens $95
warranty - one year (shipping extra)
See Focal Point in the USA which also recoats lenses, repolishes them, handles fungus and hazing problems, and so on.
I have been advised that Ultraflat Corp. will
grind and polish and recoat lenses, a service they provide primarily for
the movie business. They provide a free estimate and examination
service.
Edmund Optics (formerly part of Edmund Scientific Inc.)
can provide a variety of coating services on a custom per-job basis. See
posting to learn more about:
http://zzz1.net/rd/rd.asp?ZXU=845&ZXD=86085 - visit our website for more information!
Visit http://zzz1.net/rd/rd.asp?ZXU=845&ZXD=86085 to read more about our coating capabilities!Our Coating Selection Includes:
Visible Broadband AntiReflection Near-Infrared Broadband AntiReflection Extended Broadband AntiReflection V and 2V Narrowband AntiReflection Single Layer MgF2 Broadband High Reflectance Narrowband High Reflectance (Notch Filter) Dielectric High Reflectance Aluminum Coatings Silver and Gold Dielectric Laser Mirror Dual Laser Line Mirror Hot and Cold Mirrors Broadband Visible Beamsplitter NIR & Telecom Non-Polarizing Beamsplitter Non-Polarizing Coatings Brewster Plate Polarizing Broadband and Laser Line Cube Polarizers High Efficiency Telecom Polarizing Filters Long Wave and Short Wave Pass Bandpass
For Australia resources, try:
Longman Optical
Ian Mansfield
Technopark Centre, Dowsing Point
Glenorchy Tasmania 7010
Ph. 03 6233 5505
45 years in business, camera lenses repolished, doublets recemented,
coated with MgF, aluminising of mirrors, with silicon monoxide
overcoating, collimation. [from posting]
How is the cost of repair computed?
The above lab will give you an estimated cost if requested. Some users
report being charged $15 to $20 per surface for lens coating. That sounds
cheap, but even a simple five element lens will have ten optical surfaces
to be coated. Refiguring a scratched lens surface may add even more to
your cost. Naturally, all this precision optical work carries a high
hourly wage and huge overhead expense that you have to pay for too.
Is there any danger the lens will be lost or destroyed?
Yes, there are always risks. Older lenses may have stress lines or hidden
fractures which will become all to evident when removed from their
optical adhesive mounting. The lens element can literally crack and
fall apart. The risk of a
broken lens is reportedly very small, but it is still a risk.
What sorts of problems can be fixed with lens polishing, refiguring,
and recoating?
- Most lens killing problems can be fixed with this radical lens surgery,
including:
- scratched lens
- scratches in coating
- flat spots worn in lens
- etched fingerprints or other spots
- fungus growth etching of lens elements
- separation of edges or center of lens
Do each of the above always involve an expensive process?
No, obviously not, as it depends on the nature of the problem. A light
fungus growth problem might be easily killed with some ultraviolet light
and a bit of disassembly and cleaning. A thumbprint might be removed from
a lens front coating, and a new coating reapplied only on that one surface.
But even such minor repairs will involve a good bit of skilled optical
testing and alignment to ensure required performance is retained and
achieved. The major costs of disassembly, testing, and re-assembly are
still the big cost drivers, so even minor repairs can still cost a lot.
Why are there so few recoating facilities available?
Doing the job right takes a huge investment in trained staff and
facilities. One of the biggest limitations is the lack of test plates
required to check the lens curvature at a very high degree of accuracy.
For each lens surface, you require a different test plate. Placing the
lens in contact with the test plate in an optical setup shows fringe
patterns. These fringe patterns reveal the accuracy or trueness of the
lens curvature to the desired lens figure shape.
Now recall that each
lens may have up to a dozen optical elements, each with front and rear
curvature that has to be verified and maintained. If any of these
surfaces are off even a few wavelengths of light dimensionally, your lens
may lose sharpness, contrast, and overall performance.
Now recall all the lenses out there, and the tremendous number of optical
designs and related lens sizes and curvatures in use over the last fifty
years of lens manufacturing and design. Think about all those former
manufacturers who have gone out of business. Imagine trying to get a
stock of test plates, accurate to wavelength of light dimensions, to get
into this business. Now you see why so few lens repair and recoating
facilities exist today.
It is also worth noting that the lens doesn't stand alone. The mechanical
mounting also has to be right and properly aligned, usually to dimensions
measured in ten-thousandths of an inch. So an optical lab is no good
unless you also have all the mechanical equipment and knowledge needed to
preserve the mechanical support and operation of the optical elements.
Finally, even if the mechanics are great and the lens curvature and
coating restored to an ideal state, you still have to reassemble the lens
correctly. This process requires precise re-alignment of the optical
elements, usually on an optical bench. Moreover, some elements have to be
cemented together with precise thicknesses of optically defined adhesive.
These adhesives range from the older Canada balsam to the latest optical
adhesives that science can produce.
What about separation? discolorations?
Separation is usually the result of an older adhesive between the lens
elements literally separating away from one or more glued elements. The
process is most often seen at the
edges of optical elements cemented together. A related problem in older
adhesives is optical discoloration, often towards a yellow
coloration.
Both of these defects can often be fixed by disassembly of the len elements, cleaning, and reassembly with the proper thicknesses of the right optical adhesive, and in precise alignment. Again, this repair is one that many experienced lens repairpersons can perform using a relatively simple optical bench and tools.
Why isn't multi-coating recommended?
Cost effectiveness of multi-coating over single coated lenses is very
low. A typical glass to air interface might pass 65% of the light
striking it in an old lens design. Add one layer of optical coating, and
that figure will jump to 90% or more. Add three to five or even more
layers, and you only raise that figure to perhaps 95%. So it really costs
a lot more to get multi-coating, and the benefits usually aren't worth
the efforts.
How was optical coating discovered?
Basically, observations of older lenses revealed superior optical
performance over new lenses of the same design. This result isn't what
you would expect. Study revealed that the older lenses had developed a
thin layer of oxidation or discoloration which greatly improved their
optical light transmitting properties. This discovery was finally put
into widespread practice just before the second world war.
How is a coating applied?
Optical coatings are usually very thin layers only a few dozens of atoms
thick applied to the optical
glass surfaces. Early coatings used calcium or magnesium fluoride. The
coating is applied by deposition in a vacuum, requiring the use of a
large and expensive vacuum chamber device.
In commercial practice, large numbers of lenses are processed at once to
reduce costs. Proprietary formulas for coatings are kept secret by the
various manufacturers. Many improvements have been made, especially in
the hardness and durability of coatings over the last fifty years.
| Multi-coating Lens Colors |
|---|
| From Shutterbug Lens Flare Definitions and
Solutions by Don Garbera, p. 38, March 1989 The color of multicoating on your lenses indicates the complimentary color of light the lens' multicoating is designed to control; purple, red and blue reflections mean that the coatings are controlling green, blue and yellow light... |
How does multicoating differ from a single lens coating?
Multicoating is obviously multiple layers of coatings applied to the same
lens surfaces. But a single lens coating is a compromise of a specific
single thickness which is optimal for only one narrow band of visible
light. At other wavelengths, the optical coating is less than optimal.
Multicoating uses not only multiple coatings, but also different
thicknesses and even different chemistries of coatings. This approach
makes it possible for multiple bands or colors of light to be channeled
into the underlying optical glass, rather than reflected off the
surface. As a result, you get additional improvements in lens
performance with multicoating over a single coated lens design.
Are all modern lenses multicoated?
No, largely due to the costs involved and nominal benefits in some
applications. A good example is the popular series E lenses made by
Nikon, such as the 50mm f/1.8 series E lens. These lenses are reportedly
not multi-coated as one of their cost saving design features. The
relatively simple lens design and limited number of elements and air to
glass interfaces makes this tradeoff possible. A zoom lens, with many
more air to glass interfaces to scatter light, might not do as well as a
simpler lens if we failed to multi-coat the zoom lens optics.
Will coatings convert my older uncoated lens into the equivalent of a modern optic?
From Modern Photography, November 1980, p. 18, View from Kramer column:
My protars are beautiful, but they are anything but crisp. Their contrast
is less than impressive, and having the lens coated (as I have) doesn't
help much. Coating has no effect in the scattering of light within the
glass. It cuts down on reflections between air spaced elements, but the
lower contrast of old lenses is a result mostly of poor scattering
characteristics due to the qualities of the old optical glasses. Generally
they [older lenses] are softer and flarier than modern lenses.
What about prisms used in cameras and binoculars?
Most places that can recoat lenses can also resilver prisms used in
cameras and binoculars. Some older books even have techniques to
resilver prisms or mirrors, usually using various poisonous chemicals
(not recommended!). Really advanced telescope makers could even make
their own vacuum sputtering chambers to resilver mirrors. A large current
through a thin aluminum wire in a vacuum could sputter enough aluminum
atoms to coat a nearby telescope mirror or prism. As you can guess, this
is a lot easier than refiguring an optical lens, but no cakewalk either.
Robinson's
Antique Hardware and
Mirror Resilvering Site
What is the cost of a prism cleaning and resilvering typically
run?
It varys with the number of prisms. A simple, single prism cleaning and
resilvering might cost $50. A more complex set of binoculars, many of
which have four prisms internally, might cost $125 up. Coating the
two primary lenses on older binoculars might add $75 to that cost too.
Why are prisms such problems in older cameras?
Older cameras literally used silver to form the reflecting surface on the
prism. Silver oxidizes in air, as any housewife will attest. The coatings
are thin, and there is a tendency for thermal creep and other effects to
cause separation of the silvering from the underlying glass prism.
Why are newer prisms brighter, or what about aluminum prism
coatings?
More modern designs usually use a more robust layer of sputtered aluminum
instead of silver on prisms and mirrors. The aluminum is reported
brighter, cheaper, and longer-lasting than silver, with fewer separation
problems. Certain other reflective metal elements are also used, but
much less frequently that the cheaper aluminum coatings.
Astronomical mirrors are one popular type of mirror employing such front
surface aluminum coatings in modern designs. These soft aluminum coatings
are often protected from oxidation, smog, and air-borne dust and chemical
attacks by a thin layer of silicon dioxide.
Spectrum Astro Mirror
Recoating Services
Why are older lens and coatings more often scratched than new
ones?
The older coatings were softer than the very latest protected coating
technologies in most modern proprietary coating designs. Some sources
suggest a nitride or similar coating is often used to protect the softer
coatings (see below). A related factor
is that older glasses were often softer and more scratch prone than some
of the more modern glass formulas. So older lenses were more prone to
scratching both the coating and the glass itself.
A final factor is the much greater prevalence and use of protective UV filters on many amateur and even a few professional lenses. Multicoated filters are available, at substantially higher cost, with all the optical benefits that the above discussion would imply for them. A lens cap is probably even cheaper and better insurance against scratches too.
What about aluminum coatings for front surface
mirrors?
Front surface mirrors are often used, for example in the flip-up mirror
on most 35mm SLRs. These surfaces are very susceptible to destruction as
they are soft and easily scratched and etched by acids deposited with
your fingerprints. These same acids can also etch the front surface
coating and glass of lenses.
In general, it is much cheaper to replace the front surface mirror than
to get one repaired by cleaning and resilvering.
Much of the above has been abstracted from:
Roger Hicks' I Spy 8 Feb. 1995 pp. 26-7 British Journal of
Photography
Related Postings:
[Ed. note: A useful test tip from a noted camera repairperson]
Date: Mon, 26 Jan 1998
From: Richard Knoppow [email protected]
Subject: Re: [Rollei] Cleaning Tessars
The way to tell if the lens has gotten hazy is to open the shutter and
shine a flashlight through the lens. Any haze or other crud in the lens
will become immediately apparent. Also check the finder lens. Haze there
will reduce the contrast of the finder image and make it harder to focus.
Cleaning the finder lens requires actually more disassembly than the taking
lens and will also require re-setting the correlation between finder and
taking lens. The is perhaps better left to a repair type person.
----
Richard Knoppow
Los Angeles,Ca.
[email protected]
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