Re: King of viewers & Achromat StereoScope Message-ID: <19960810140332.AAE19957@xxxxxxxxx>

[P3D Dr. George A. Themelis <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx> To: photo-3d@xxxxxxxxxxxxxxx]

dlewis@xxxxxxxxxxxx (P3D Alan Lewis) wrote: 

> Plus a short article in the Q-VU Gazette on the new Achromat > scope. Did you catch the first line in the article (written by Quentin Burke):
> "Contemporary stereoscope guru Alan Lewis has come up with......." Now I ask you, is
> being a "guru" close to being a "king" of viewers, or do I have to keep working at it?

Hey, there can be many gurus but there is only one king!!! ;) 

> I am very pleased with the results from the prototype. The achromats really do a better
> job than any PCX or DCX single element lens. The views appear to have more depth and
> much sharper edge definition. Some doubt was cast on the effectiveness of achromats in
> a Holmes viewer because the focal length is long and the benefits may not be readily
> apparent, but they are noticeable.

I was under the impression that the reason that achromats are not used in stereoscopes (as they have been used extensively in stereo slide viewers) is that,
unlike the spacing of Realist format chips, the spacing of the stereo viewers in a standard stereo view is wider than the spacing of the eyes. Some kind of prismatic lens is needed in the Holmes stereoscope to diverge the light path. 

How do you go about using achromats? You are not cutting them in half, are you? Do you just use large lenses? I have been able to view stereo cards using achromats of large diameter. The large focal length makes a slight divergence easy to achieve.

George Themelis


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