RE: 3D Wizards

[P3D Gregory J. Wageman <gjw@xxxxxxxxxx>]

Larry Berlin wrote:

>Of interest was the evidence of a lack of symmetry in the camera. Since I
>had prints made from the film, I laid them all out on a table in triplets.
>(3 lenses - 3 prints) Then by cross-viewing I looked at all the images. Each
>set of triplets results in two stereo images side by side. What was
>surprising is that for a significant proportion of the images, the pair on
>one side was more distant than the pair on the other side. This could only
>be due to the lenses not being precisely placed. However this did not show
>up in all images. I'm at a loss to explain why.

I can think of two other reasons to explain what you saw, other than
variances in the camera's lenses.  Since these were prints, there's
the possibility that the enlarger was adjusted slightly during printing,
which would change the size of an image, but if this were the case
you should be able to see it for example by superimposing the prints on
a lightbox.  The second possibility is that if the prints were different
distances apart when you cross-viewed them, your brain was interpreting
the different convergence required as a difference in distance (and
therefore, size).

	-Greg W.


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