P3D In search of the best stereo viewer...

["Dr. George A. Themelis" <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Al Knecht is asking for the "best" viewer for 41x101 standard stereo 
slides.  

This subject is of great interest to me... I have a series of books on 
specific stereo slide viewers and I am working on a book on viewers in 
general, which I hope to complete in a year or so.  In the NSA 
convention I presented a workshop on stereo slide viewers. I have 
written a series of articles in Dalia's "Inside 3-D" magazine and I am 
now working on an article on current developments on stereo slide 
viewers for Stereo World.  You would expect that with all this 
activity, I would be able to answer this simple question... but I 
can't!  There is really no clear-cut answer or we would all be using 
the same viewer!  :-)

For example, if I tell you that the best viewer is the deWijs "Comby"
viewer w/the deWijs power supply, would you be willing to pay $1200 for 
it?  You see, I noticed that "reasonable price" is missing from your 
list of aspects of the viewer you are looking for.  And, the worse part 
is that after you get this viewer you might not even like it!!!

For some details now:  I like to break down viewer components into 
three parts: 1) Optical, 2) Mechanical, 2) "Electrical" (illumination).  

Optical:  The least expensive viewers have single-element lenses.  Top 
of the line viewers of the '50s have achromats.  IMO, achromats is the 
minimum you should demand in a viewer.  But, I know people who, for 
various reasons prefer a Brumberger to a Realist red button viewer.  

You wrote:

>I recently sold my White-button Realist viewer for a premium and 
>replaced it with a Red-button. But I did not notice much increase in 
>clarity or less distortion when contrasted against the single element 
>"white button".

The white-button Realist viewer has single-element lenses, while the 
red button viewer has achromats (assuming that there has not been a 
lens replacement).  For me, the difference in quality is very obvious. 
The single-element lenses show very clean (and annoying for me) 
chromatic aberration (false colors -usually blue- around the edges) 
and considerable distortion.  But, quite a few people cannot tell the 
difference. 

>On a side note, I bought a Revere22 and was not impressed with the 
>optics at all.

I wonder why... I think the Revere is a fine viewer and the optics are 
among the best.

To complete the optics, in my opinion, achromatic lenses are much 
better than single element lenses and good enough to make most people 
happy.  The deWijs viewer I mentioned earlier uses double-achromats.  
The advantage of this configuration is that you can get a large 
diameter to focal length ratio or large lenses with high magnification
(short focal length).  Large size makes viewing more comfortable, 
especially for people who wear glasses.

To be continued...

George Themelis