[photo-3d] Re: viewer optics

["John Goodman" <jgood@xxxxxxxx>]

Peter Abrahams wrote:

>    The Red Buttons are quite sharp mid field ... But away
> from the center of the image, they show slight distortion
> (curved frame), astigmatism (fuzzy edges), and curvature of
> the field 

In my (limited) experience, I've found considerable difference 
between average red button Realist viewers and later examples, 
the legendary Realist black button viewers. Though the 
specifications are identical, even when viewing 5p stereos there 
are certain Realist viewer lenses that offer a noticeably flatter 
field, greater peripheral clarity, and more viewing pleasure than 
their brethren. Unfortunately, they are scare and are spoilers, 
but do help when viewing wider than 5p in doctored Realist 
viewers.

On another front, while examining some relatively large 
diameter loupes in the 5X to 8X range that attempt to cover 
35mm full frame with minimal distortion, I noticed that the 
best performing ones have a planoconvex lens element with the 
flat side extremely close to the plane of the slide. These are 
expensive and might be difficult to adapt for stereo viewer use, 
but such designs seem to offer superior performance.

jeg

 

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