Re: [photo-3d] Looking for a decent/large projection screen

["John A. Rupkalvis" <stereoscope@xxxxxxxxxxxxx>]

Yes, you are quite correct about the reason for the orientation of the
lenticules (and purpose of them).   A flat silver (aluminized) screen works
very well for polarized 3-D, but it is very directional.  This results in a
brighter image in the center than the corners, and a narrow dispersion angle
(people sitting at the sides of the seating area see a very dim picture).

The vertical lenticules spread the light to the sides.  If the screen
material were the other direction (horizontal lenticules), much of the light
would go to the floor and ceiling and be wasted.  Actually, special
lenticular screens have been made for auditoriums that have balconies or
stadium seating.  These have crossed lenticules running both directions.
But, when the audience is all on one level, this would again waste light.

Da-Lite screen company has some good, knowledgeable 3-D people on staff, who
can answer many of your questions.  One of these is a fellow by the name of
M. K. Milliken.

A few years ago, Da-Lite acquired Polacoat from the 3-M company.   As you
might deduce from the name, the Polacoat line includes screens designed for
polarized projection.  The Polacoat screens, however, are translucent
screens intended for rear projection, as opposed to silver screens which are
for front projection.  Da-Lite is in the central part of the U.S. (Ohio), a
consideration when having larger screens shipped.   They also cater mainly
to industrial and individual consumers, although they have been making a
dent in the theatrical market as well.

On the East coast is the Hurley Screen company.  Although I haven't checked
lately, they did carry a silver 3-D screen material at least at one time.
Maybe they still do.  They sell almost entirely to the theatrical market.
Primarily the material is intended only for "lace and grommet" mounting to a
rigid frame that surrounds it on all sides (not rollups).

The West coast has the Stewart Screen company.  Very similar to Hurley in
both product and marketing (lace and grommet types for theaters), they
recently have entered the upscale home theater market.  They also have a
silver 3-D material.

There are some others.  Raven and the Draper Shade (!) company come to mind.
I don't know what their current status is regarding silver screens.
Somebody might like to check web sites and check out these and any others
that can be found.

Used screens may or may not be a bargain.  Often they are severely marred or
otherwise damaged when they are dismounted.  Silver screens often crack if
they are rolled up after hanging for several years.  If not then, they may
when unrolled.  Caveat emptor.

Some people have made their own silver screens by spraypainting an old white
screen or even a white wall with silver paint.  But, to work it must be a
true aluminum metal flake based paint, not just any old paint that happens
to look silver because of the pigment being tinted that way.  You can test
it by spraying a small test patch and taping a polarizer on a flashlight.
Looking through one eye lens of a pair of polarized glasses, the light
reflected off of the patch should completely extinguish when the flashlight
is rotated.   Again, I don't know the current status, but a few years I
bought a "bright silver" spray paint from Sears that worked quite well.

Another caveat: the paint must be applied extremely evenly; several very
light "dusting" coats applied in different directions crossing each other.
Preferably this should be done by a very experienced professional spray
painter.  I have never been able to get it even enough myself, but I have
seen professionals do a very good job of it.

No matter which route you choose, one thing you can be sure of.  If you want
a good large stereo screen, it ain't going to be cheap!

JR
-
---- Original Message -----
From: "Gabriel Jacob" <gjacob@xxxxxxxxxxx>
To: <photo-3d@xxxxxxxxxxx>
Sent: Tuesday, October 10, 2000 1:33 PM
Subject: RE: [photo-3d] Looking for a decent/large projection screen


> Dr.T writes:
> >This limits the length of the screen because the ridges must be
> perpendicular.
> >So you could get it taller but not longer.  I asked why did the ridges
have
> to be
> >perpendicular and they told me that this is how it should be.
>
> My guess is the ridges have to be perpendicular because the audience is
> sitting left to right (of the screen).
>
> >Questions:  What do other people/clubs use?  I would like to hear some
> >suggestions for larger screens.
>
> Wasn't Ron Labbe selling some screen material suitable for 3-D? I remember
> he was promoting this at Richmond (NSA 98 convention).
>
> Maybe John Rupkalvis has some leads?
>
> I wonder where Imax gets their screens from? Funny thing about those
screens
> is that you can see right through them when they are back lit. I was able
to
> see
> this when they had a demo of the Imax system and had a show laser light
show
> before the main feature. I wonder how does that impact on their reflective
> efficiency.
>
> I think someone on this list had posted they got old Imax (or another
> theatre)
> screen material for almost nothing when the theatre was upgrading their
> screens.
> Lucky guy (or gal)!
>
> Gabriel
>
>
>
>
>