P3D Re: Rear screen projection, etc.

[Tony Alderson <aifxtony@xxxxxxx>]

"Dr. George A. Themelis" wrote:

> Anyway, he mentioned that he is has done "split frame stereo" (this
> means "beamsplitter" format) seen in rear screen projection.  He
> said that if you match the focal length of the projector lens with
> that of the taking camera lens then you eliminate any keystone
> distortion.  

This doesn't sound too implausible; isn't it true that you can correct
the keystoning of toe-in photography by toeing-in your projectors at a
similar angle? Of course, you're stuck with a fixed convergence in the
system for this to work (and I'd guess in this particular case, a fixed
projector throw.) Rather limiting, in my opinion. Don't offhand see how
the focal length matters...well, wait, he's using a single projector
(not two), so maybe that's right. 

> 
> He swears that the experience is unique.  He mentioned that
> a firm in CA: "Stuart Film Screen Company" sells rear projection
> screens and encouraged me to call their number 310-784-5300 or
> 1-800-762-4999 to get literature and samples.  He says this company
> deals with the Pentagon and corporate conference projection setups
> and their products are very good.
> 

Stewart Film Screen is a reputable company, and has done all kinds of
custom screens for special effects work, theaters and so on. They've
been around a long time. They make some excellent silver screens for
stereo projection, I've only used their rear-screen material in 2D
effects work. Marshall Stewart (who left the company some years ago)
used to be an active member of the Stereo Club of Southern California,
but I haven't seen him for a while and have lost contact. Regardless of
the ideas of the guy George talked to on the phone, Stewart Film Screen
is worth checking out if you need their (professional) products.

Tony Alderson