P3D To toe-in or not toe-in

[fj834@xxxxxxxxxxxxxxxxxxxxx (Dr. George A. Themelis)]

>> most literature states that cameras should not be 
>> toed-in, but our eyes do "toe-in" when we look at something close-up 
>> to our faces.
>
>This is true, however according to the books I've read, the stereo
>photographs we take don't have the camera lenses "replacing"
>our eyeballs -- but instead, the photographs are intended to present
>the "environment" which our eyes live in.  So although our eyes may
>"toe-in", it doesn't matter to the reproduction of that environment.  

That's a good way to put it.  Also, our eyes toe-in when they look
around the stereo pair.

>They go on to explain why using toe-in  creates undesired distortions 
>and that it should only be used when necessary for practical reasons.

I agree.  In the case of base-to-base mounted cameras, a little toe-in
might be necessary in order to be able to mount the slides in a Realist
format mount.  This becomes particularly important when 135 mm or longer
lenses are used for close-up (like portraits).  This is the idea behind
the Jasper bar and if Tim wants to take portraits or close-ups with
longer lenses I think he will find this toe-in-ing necessary.

>Not that the distortions are necessarily noticable or particularly
>distasteful (although Boris may disagree). 

It is all a matter of degree.  I have produced slides by toe-in-ing
200 mm lenses on a small statue and the keystone distortion at the edge
of the frame was unbearable.  On the other hand, the portraits taken
with 135 mm lenses on bottom-to-bottom cameras did not show any noticeable
distortion.

-- George Themelis


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