[photo-3d] Re: screen shapes

[Bruce Springsteen <bsspringsteen@xxxxxxxxx>]

Brian Reynolds
> Bruce Springsteen wrote:
> > Regardless of width, the various (usual) 35mm stereo formats (4P, 5P,
7P,
> > 8P) have one thing in common: the height of the image.
> > 
> 
> That's only true for horizontal compositions.  An 8P vertical
> composition (e.g., taken with a pair of 35mm cameras twinned base
> plate to base plate and projected in 2x2 mounts) will not have the
> same height.

Oh, I see.  I missed the meaning of "vertical" in the discussion, thinking
it referred to conventional 3D formats with greater height than width. 
Jim Norman's interest in the discussion - the man who accepts no limits to
height and a giant among stereographers - should have clued me in. ;-) 
Yes, that presents some difficulties.  I guess as in so many other things,
a screen that suits all possible formats equally well is inherently
impossible, and someone will always be slighted - usually the minority.

Given that, I'd think that most clubs will want the screen shape that best
accommodates the most common formats, with as little variation in stereo
geometry as possible when switching from one to another - hence my concern
for consistent magnification on screen, and adaptive masking if desired. 
(Some small solace: even if vertical views like Jim's were interspersed
with regular 2x2's, decapitated and bleeding on some Procrustian screen,
at least the degree of magnification would be constant.  Don't "zoom" him
in a misguided lunge for mercy, the "stretch" could be fatal!)

Anyway, Grant seems to be honed in on the best compromises for his club's
needs.

Now that PVC frame *could* have a pivot in the rear to rotate the screen
from horizontal to vertical on a moment's notice, if we're determined to
please the misfits like Jim...

Bruce (Still can't take dictation!) Springsteen

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