T3D Re: Bugs In 3D

[john bercovitz <bercov@xxxxxxxxxxx>]

I don't know the answer to your question, unfortunately, but I'm
as curious about it as you are.  Perhaps someone else on this list
knows of a variable-base macro camera.  The only thing I can think 
of is two cameras plus mirrors (one of which would be half-silvered).
See Ferwerda.

I find something here that I would take issue with but perhaps it
is only a matter of symantics:

> "For each image, the base was selected to produce a 
> natural (orthostereo) effect without exaggeration."

To me, orthostereo implies that the taking base matches the viewing
base and the taking focal length matches the viewing focal length.
So by my defintion of ortho, which I think is pretty common, the 
quoted statement is incorrect.

This is absolutely pure speculation on my part, but it is possible 
that PePax is being referred to.  PePax says that as the base is 
increased, so must the magnification be increased.  Therefore 
if you use a taking base which is half normal, you must use half 
the normal magnification when viewing (and vice versa, of course).  
PePax was common thinking in the thirties; you can even read about 
it in JOSA!  Anyhow, as charming as the idea is, when you do the 
geometry, it doesn't work.  For a more complete explanation, see 
Ferwerda or Piper.

John B


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