Re: Stereoscope optics question

[P3D Gabriel Jacob <jacob@xxxxxxxxxxxxxx>]

John Bercovitz writes

>The closer the separation of the lenses' optical centers is to the
>IPS of the individual, the better the resolution because the
>resolution looking through the center of a lens is better than the
>resolution looking through its margin.  

I have often wondered about this, regarding the resolution, etc.
As you mention the max. infinity point separation should match the
lenses optical centers. You continue and say, the eye can be placed
anywhere in the emerging rays' field but that the center of the
lenses have higher resolution than the outside part.

Everything you said made sense but would just like to ponder a bit on
it. The part that I always wondered about but never read specifically
about or not expounded upon very clearly is in design of 3D viewers
(except on P3D ;-)). Intuitively one would think that the lens optical
centers should be the same as the IPS. Of course this is not the case
as you mention, as it is not necessary but the sacrifice is usually
resolution due to the light rays being more "distorted" at the
curvature of the lenses. This is even more pronounced with aspherical
lenses I think. Ideally to solve this as others have mentioned other
than making larger diameter lenses with it's inherit problems, would
be to be able to match the lenses and the views so that they can be
adjusted together simultaneously. Of course this is not usually
practical. Another method is to actually adjust the lens optical
centers to the IPS. Of course this brings other problems if the
spacing of the lenses and eyes are not the same as the infinity
spacing. This results in making viewing uncomforatable and tiring
and in some cases unable to fuse the images among other things.

There seems to be two schools of thought regarding on which way is
practical other than, adjustable lenses coupled with the views. Larger
diameter lenses with corrections for the different aberations OR
adjustable lens separation. The opinion that adjustable lenses to
match the IPS is not needed, usually assume that the lenses in
question are of good design and large diameter and won't intefere
with the sharpness of the view. Of course this is not always the case.
It seems to me that if the lenses are either smaller diameter, simple
lenses or aspherical then adjustable lenses spacing to accomodate IPS
is the preferable tradeoff. And this is why I think it is done with some
viewers. Any differing opinions or corrections gratefully accepted.

Cross-eyed.

       Ga  br  ie  l       G a b r i e l
     _    you     _      _      you   _ 
   /  \seeing    / \    | \   seeing  |\
  /     _       /       |      _      | 
 .----./ \.----.        .----./ \.----.
 |3D  /   \3D  |        | 3D /   \ 3D |
 '---'     '---'        '---'     '---'
  



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