P3D Re: 6x9cm stereo viewer: is it possible; has it been done?

[Paul Talbot <ptww@xxxxxxxxx>]

Dogbreath wrote:
 
> Would love to view stereo pairs of 6x9cm chromes in a handheld viewer.
> Perhaps 6x7 is the limit without the use of some pretty fancy mirrors and a
> prism. It seems to me that the center-to-center base of two 6x9 images side
> by side is larger than the average human interocular.

Yes it is, but the average Holmes stereocard is also spaced wider
than the average human interocular.  Depending on how much space
you want between the left and right image, you're "only" talking
about 1/3 to 1/2 inch wider separation than a Holmes format card.

> I wonder what the
> smartest solution to such a problem would be. Is it a foolish idea? 

I don't know about the "smartest solution" but the easiest
solution would be to put the chromes on a lightbox and use
a ViewMagic viewer, or an Alan Lewis "pocket stereoscope"
(aka "Freeviewer's Assistant").

To go to a handheld viewer, keep in mind that the lens
spacing must be equal to or greater than the infinity
point separation of the images.  You're going to need a
mighty big diameter lens to allow a person with normal
eye spacing to see through lenses that are set on 3.75"
centers--possibly close to a 3" diameter lens.  This only
addresses the basic considerations.  I have no idea what
kind of excessive viewing distortions might arise in such
a setup.

I'm curious to hear what others have to say on the subject.

Paul Talbot