T3D Re: A Third Simple One

[john bercovitz <bercov@xxxxxxxxxxx>]

> Reasons for 1.2mm maofd (the "aim" stated in the article) on 35mm
> format seem to boil down to two issues:
> 
> 1.  The difference between window deviation and infinity separation in
> the Realist mounting/viewing scheme is arbitrarily 1.2mm.  If you
> don't want to come through or violate the window, and don't want
> divergent infinity, that's the limit.
> 
> 2.  It reflects some average limit in the human visual system for
> "comfortable" stereo viewing of scenes with large deviations between
> near and far subjects (perhaps definable as an angle?)
> 
> Number one seems obvious.  But number two confuses me.  Is this limit
> of comfort documented?

I think #2 preceded, and was the reason for, #1.  I infer that experiments
were done but whether they were documented in other than proprietary files
I don't know.  A lot of us have done experiments with different amounts of 
on-film deviation for different types of scenes and feel pretty comfortable 
we know what will work and what won't.  In my experience, 1.2 mm is easy 
for everyone to view and sure-fire for any scene.

I expect Abram would more likely know if anything in the way of controlled 
experiments has been publicly documented.  If it had been written in the 
scientific literature, Jim C would know of it, and he hasn't mentioned it, 
so I doubt it's been written there.

John B


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