P3D Projection problem

[Paul Talbot <ptww@xxxxxxxxx>]

I have finally joined the ranks of the stereo projector
owners!  Yeah! :-)  (Much thanks to local stereo enthusiast
Gary Nored who found a TDC116 at an estate sale.)

However, I've not yet been successful at projecting.  :-(
I'm getting such extreme ghosting that the images are
effectively unviewable.  The problem seems to be lack of
(or insufficient) extinction in the right-eye view.  My
initial reaction was that the right polarizer must be at
fault.  But when I place a pair of polarized glasses in
front of the projector lenses, the screen goes completely
dark.  This suggests the polarizers in the projector must
be OK, right?

I'm left with suspecting a problem with the screen, which
was given to me about 1-1/2 years ago.  It is a silver screen,
brand name "Radiant Glo-Master."  I find that if I project
one side at a time, the image on the screen is mostly still
viewable with either eye, though one side is slightly dimmer
than the other.  Is that damning enough evidence, or am I
misinterpreting something?

With only "near" archive searches currently operable, I'm
not having much luck finding an answer in the archives.  I
note that Peter Abrahams wrote in his excellent "Ghosting"
summary, PHOTO-3D Digest 2202, Tue, 29 Jul 1997:

> Metallic, silver screens are required.

Does this mean "metallic silver" or "silver or metallic?"

Also, on Oct 2, 1997, in digest 2332, "Sandman" wrote:

> (I am using a very old silver screen that ghosts a lot).

Do silver screens "wear out" with time and/or use?

Given the common advice to pick up cheap silver screens
at thrift stores, if problems with silver screens causing
depolarization are common, how does one avoid buying, say,
1/2 dozen "bad" silver screens?

Any and all assistance in these matters will be much
appreciated!

Paul Talbot


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