T3D Re: TECH-3D digest 415

[Eric Goldstein <egoldste@xxxxxx>]

Lme Kbee asks if his Stereo Vivid by TDC has such vibrant
colors because it has coated lenses. Bob H replies that the Vivid may
have been multicoated, an important fact to try to varify. Does anyone
know difinitively whether the Vivid glass was multicoated?

Bob conjectures that multicoating shouldn't help produce vibrant colors.

John B sez:

> As to why coating helps, it's all a matter of contrast.  If you
> don't have coating, you have a lot of excess light scattered all
> over the film and that is the equivalent of preflashing to reduce
> contrast, as one way of thinking of it.

Do we know whether increased contrast produces an increased perception
of color saturation? We know definitively that higher contrast
ordinarily yields a perception of greater sharpness. Anybody ever come
across any research on this?

Another possibility for the Vivid's higher color saturation (if real and
not a function of exposure, emulsion, lighting or perception
differences) could be a difference in glass. If the Vivid was
multicoated, it was manufactured later than most other stereo cameras
and so may benefit from a recalculated lens formulation using higher
index glasses. I know for example that Zeiss recalculated the Tessar in
the 60s to take advantage of newly available/affordable higher-index
glasses, and it yielded lenses which were close to apochromatic. This
made for (among other improvements) better color fidelity.


Eric G.


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