The reason I ask is that I currently own the DALite and although it is a good screen I have been bothered by a few qualities of it. I purchased it before I realised the impications of a pull down, glass beaded screen.
Some of the things that have become most distracting to me are picture geometery, and hotspotting.
Obviously Geometery can be fixed by using a fixed screen.
Colour shift really doesn't bother me much at all, it is only really apparent in a blue sky scene and not really distracting for me.
What does bother me, (and seems to vary a lot from scene to scene, from basically un-noticable to fairly extreme) is the hotspotting. I notice on some material darker corners. Will this be as evident with the M2500? Is the M2500 as bright or brighter? Can anyone make any suggestions of other changes I would notice by going to the Draper, or perhaps recommendations of another screen type?
These pics can be seen at www.mindspring.com/~daalcorn
I reall enjoy the Draper M2500 as it seems to really allow a brighter picture, with a lot more contrast and vibrant colors. I see no hotspotting when I'm watching movies or TV programming. The only time I can see some minor hotspotting is with an All White test pattern. But even then it's virtually a non-issue.
The Academy Home Theater
The hotspotting is visible with the center being slightly brighter than the edges, but the brightness gain is worth it for me. I don't really notice it while watching movies, but you can see it with some flat color fields and some test patterns.
I needed to go with a higher gain screen because of the screen size, but I had heard bad things about glass beaded screens in terms of the problems that you mentioned and not being washable either, so I went with the M2500 and have been quite pleased with the results.
An screen in a front projection system is an intrinsical, critical part of the optical equation, and is one that shouldn't be compromised...if accuracy is sought after...so choosing an screen is of paramount importance...
Frank is correct. A glass-beaded screen is not appropriate for a home theater. You are definitely on the right track by thinking about going to a fixed screen application. The fixed screen will allow you to use a stretched vinyl fabric rather than one that has a fiber-glass base to it. This makes for a much flatter screen with no edge curls etc.
However, to answer your question about the material. The glass-beaded fabric you have is a 2.8 gain screen. The Draper M2500 is a 2.5 gain screen. The biggest difference in the two is the fact that the Glass Beaded is retro-reflective and the M2500 is reflective. What that means is when light hits the glass beaded screen it bounces back in the same path it arrived. Conversely, when light hits the M2500 it bounces back at an angle equal and opposite that of which it arrived. If your projector is ceiling mounted, you need a reflective surface not a retro-reflective one.
Now on to the question of gain. You mentioned the Draper M2500 fabric and as I stated earlier it has a gain of 2.5. That may be a little hot for your projector. You have a Barco 808 projector that is a CRT projector and is inherently non-uniform. Therefore, the higher the gain of the screen the more accentuated the hotspot is going to be. Therefore, if you have good control of the ambient light in your room a gain of 1.3 or 2.0 is preferred. However, I would not go over 2.0. If you do you will start to show the hotspot and you will narrow the viewing angle of the screen.
All three of the big screen manufacturers have screen surfaces with 1.3 gain. Both Da-Lite and Stewart's screens are ISF certified. In addition, I know that Da-Lite is one of the only companies that has a 2.0 gain surface. They call it Pearlescent. It is a reflective surface, as you will need.
Hope this helps,
See the thread entitled...Letter From Draper...
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