P3D Re: Stereo Projectors

["Greg Wageman" <gjw@xxxxxxxxxx>]

From: Michael Kersenbrock <michaelk@xxxxxxxxxxx>


>But then, with separate cheap projectors, can't one just put the one
>with slightly longer F.L. a hair further back than the other one to
>compensate for the magnification difference?

If you're stacking your projectors vertically on a stand, this may not
be an option.  For example, the dual-projector stand sold by Reel-3D and
made by Da-Lite, allows for very little, if any, adjustment.  If the
focal-length mismatch is significant, you might need a very large table
(or multiple tables) to offset them sufficiently.  And if they are
manual-feed, this can become quite burdensome.  But aside from these
practical considerations, the implication above is correct: changing the
projector-to-screen distance compensates for differences in lens focal
length.

>One can get new silver screens in the U.S. from B&H (or at least could,
>haven't checked lately) quite inexpensively.

Reel-3D still sells them as well, though they are cheaper from B&H,
which is where I got mine.

     -Greg W. (gjw@xxxxxxxxxx)



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