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

["Alfredo Gonzalez" <agonzalez@xxxxxxxx>]

About 3D screens, I saw recently an Imax 3D film at Futuroscope, 
France, and the polarized projection was impresive. I think the
secret 
is the high quality metallic paint employed, and high eficiency 
polarized filters. But the screens not seems metallic, but "pearly".
Do you know what kind of paint can be?

Alfredo Gonzalez
StereoWeb http://www.red3i.es/~stereoweb

--- In photo-3d@xxxxxxxxxxx, "John A. Rupkalvis" <stereoscope@xxxx> 
wrote:
> 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@xxxx>
> 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
> >
> >
> >
> >
> >