P3D Re: optics of stereo viewers

[Larry Berlin <lberlin@xxxxxxxxx>]

>Date: Wed, 31 Dec 1997
>From: Peter Abrahams writes:
>
>I acquire Red Buttons because they're the best available viewers for stereo
>slides.  If you open up the slide carrier windows, you can see 7 perf, but
>anywhere near the edge they are not at all sharp.   They are sharp enough
>in the middle of the field and become blurry near the edge.....not right at
>the edge, but maybe 2/3 of the way to the edge.  This is nowhere near as
>good as could be, a flat field magnifier (such as a high quality loupe used
>to magnify negatives) would give vastly better performance.

****  This is similar to my experience with Full Frame 35mm in a RED button
viewer. The extreme edges are there, but not very clearly. What was worse
was that being able to see as far as those edges, allowed me to sense the
distortion created by the optics themselves. The entire view in a RED button
is presented as if it's painted on the inside of a bowl. Just viewing near
the center, which would be typical of 5 perf, doesn't give you enough
evidence of the bowl distortion to significantly notice. With full frames,
you can definitely see it and trace the entire bowl surface with your eyes.
I'm very sure that if I used a RED button exclusively I might not notice the
bowl distortion, or would become very used to it and interpret the images
accordingly. However, that distortion is significant enough that I
definitely don't prefer RED button viewers, though they are fun and useful
in the absence of something better.


>................  It really is
>important to get good optics out there, for until you've seen the best, you
>don't know what you're missing.

****  I think you're right. But what is best, and can it be affordable?

>
>>I've got several viewers whose apertures cover 7+ perf with decent
>>internal illumination and achromatic lenses... optically they are not NEARLY
>>the equal of the camera glass and do not cover the field.
>>Sorry, but the Red Buttons DO NOT cover 7 perf, and typically have
>>marginal contrast (haze). 

*****  If you are experiencing a hazy effect maybe the viewer needs cleaned...?

Larry Berlin

Email: lberlin@xxxxxxxxx
http://www.sonic.net/~lberlin/
http://3dzine.simplenet.com/


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