Re: PHOTO-3D digest 1293

[P3D Eric Goldstein <egoldste@xxxxxxxxxx>]

P3D Michael Kersenbrock wrote:
> So.... *if* in that timeframe, lenses were often non-coated or only partially
> coated such that a more fully coated Wollensak lens transmitted 2/3'rds
> of an f/stop more than a non-coated 3.5 lens, then maybe their marketting
> department's f2.7 spec is an "equivalency" spec, meaning that it would take
> a non-coated lens of f2.7 to have the same light transmission of their lens,
> and therefore it "is" a f2.7 lens.  In marketting-speak.  :-)


Interesting thought. It's not uncommon to loose about 7-8% of the visible
spectrum to an uncoated optical surface. Let's say that the Revere Amatons were
front-surface coated only (common practice for the time). This would leave 5 surfaces,
or a potential 35-40% of loss through uncoated surfaces. 50% is a full f/stop... so
maybe!

Now, can anyone tell us if the Wollensak Anatons have all their lens surfaces coated?
(Not too likely given the practices of the time, but possible.) Here's the description
provided by Harry Poster:

> But the Wollensak catalogue states:  "...MODEL 10 STEREO CAMERA-W/coated
> 35mm f/2.7 WOLLENSAK AMATON Anastigmatic lenses in MFX RAPAX Synchromatic
> Shutters; matched in focal lengths within less then '/4 of one percent; fully
> color corrected; excellent definition and resolution without sacrifice of
> contrast; click stops for accurate diaphragm and shutter speed settings.
> Accepts standard #5 disc filters and Series VI sun shade and accessories.
> Shutter speed markings, 1/2 to 1/300 sec, T and B and lens stops located on
> top of lens mount for extra convenience. Uniform synchronized controls for
> lens stops, shutter speeds and flash; superimposed image rangefinder;
> simplified 3-arrow exposure guide; automatic flash computer; eye-level
> focusing and viewing; double exposure prevention; single frame provision
> Complete with f/2.7 lenses, inc. tax, $199.50"


No clue here. Does anyone know?

Lens coatings not withstanding, none of this changes the fact that these lenses are
triplets, and all things being equal inherently cannot match the edge sharpness
(resolution, accutance, etc.) of a tessar type at _any_ aperture, and more than likely 
their performance (with regard to this criteria) is no better than lowly $100 realists 
and kodaks!


Eric G.
egoldste@xxxxxx


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