Re: [photo-3d] viewer optics

["Dr. George A. Themelis" <drt-3d@xxxxxxx>]

I am sorry, I am not an expert in optics but I do have
a few questions....

>Instead, we should compare
>them with other types of eyepieces that were standard by the 1950s, in
>binoculars, telescopes, and microscopes -- even inexpensive models.   These
>were vastly better & show that the technology was available to produce a
>much better product.

How about if we compare them with other stereo viewers
(with achromatic lenses)?

>   The Red Buttons are quite sharp mid field, as any decent eyepiece since
>the 1700s has been.  But away from the center of the image, they show
>slight distortion (curved frame)

I think someone mentioned that even the deWijs lenses
show slight distortion.  One of these lenses costs
more than the entire red button viewer.

>astigmatism (fuzzy edges), and curvature
>of the field (focus mid field, then to focus at edge of field you have to
>turn knob)  to a degree that could have been inexpensively corrected in the
>1950s.   

Are there any other stereo viewer lenses from the 
1950s without these "features"?  If I buy a pair
of "modern" achromats from Edmund Scientific (and
pay about as much as the entire red button viewer,
just for the pair of lenses) would these problems
be absent?

>Also, they were uncoated, at a time when most inexpensive optics
>were routinely coated; and this makes a big difference in reducing
>reflections off the eye lens and overall glare.

A big difference?  I am not so sure....

>   They could also have been made with enough eye relief to allow for use
>with spectacles, 

I was under the impression that achromatic lenses
have zero eye relief, meaning that the minute you
start moving the eye away from the lens, you see
less and less.  

>   I admit that much of the problem with the Red Button as used today, is
>that we've adapted them to full frame use, and they were designed for
>Realist format. 

I use them for wide RBT slides and I don't see these
problems... sorry...

George

 

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