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I did a bit of experimenting with glass bead screens (bought from a thrift store) before I settled on my Draper M2500 screen. I found the glass bead screens produced too much hotspotting and "rainbow" fringing for my tastes. There are good reasons that hardly anyone uses glass bead screens for home theater; they are primarily useful for old underpowered slide projectors. Other kinds of high index screens like the Draper M2500, or the KBK screen goo are probably better choices. You might also want to look into the Da Lite silver screens.
 

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Look for a curved screen. I went from a glass-bead with a gain of about 3.2 that I got from a damaged freight service to a curved screen with a gain of about 10-12. Not only is the picture much, much brighter on the curved screen but the hotspotting and color-shifting is reduced (not eliminated, but definitely reduced). Geometry is a little hard to get right, but it is not terribly obvious unless you are throwing up test patterns instead of movies.
 

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I use a dalite Highpower screen. They have very small glassbeads which is as smooth an vinyl. Nothing like the normal glassbeaded screens. Has a 2.8 gain and 25 deg angle. I can't see any hotspotting with a crt, but colorshift might be a problem depending on viewing angle. I also have a standard matte white but never compared them to see if the extra gan makes that much difference in a dark room. You have to remember that a HighPower reflects also the ambient lihgt, so be sure that you have a perfect dark room to watch video
 

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I also have Dalite Highpower, I think 2.5 gain. As Boris describes, hotspotting is not a problem. The color shift however can be a bit of an annoyance- from one side of the screen I notice more blue, from the other more red. If I sit in one of those off axis positions I "get used to it" and after a few mins I dont notice it at all. Fortunately, my couch is in the middle a feet feet back from the (ceiling mounted) projector, so I rarely notice hotspotting or color shift at all. I have yet to have anyone come over who noticess any of these "artifacts," yet when I was using my RPTV everyone who sat to the side complained. (cant help but mention that with that p.o.j. RCA RPTV you could not lay on the floor and see the picture from the hotspotting. You had to be in the middle, left-right and up-down. So sad.)


The sad fact is that over time any screen is going to get dirty. If you decide on a glass bead, accept the fact that you will *never* be able to clean the screen with good results. Basically, if the featherduster doesnt take it off, nothing will.


My horror story is that I rolled my screen up with a housefly (yes, I swear it is true!)attached to it. Yuck! Long story short, the fly didnt win, but he (she?) left a lasting black spot. Fortunately it is at the very bottom of the screen in a corned. Dalite technical support suggested that "at least its a black spot. If you try to clean it with any checmicals, even water, the beads will come off exposing a bright white surface, which will be far more noticable." As a result, for me, there is absolutely no way I would ever go with another Glass Bead screen because of the cleaning issues. The first thing I will ask when I buy (or build) my next screen will be "can it be washed?"


I guess the bottom line is that if you are trying to find flaws you will, but if you are just out (orin this case "in") to enjoy a good movie you will not notice. If you are willing to live with this downside - or perhaps can aquire the screen at a disposable price - then go for it



-Kieth
 

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DONT DO IT,


I just left a glass bead. With the CRT on the floor the image was nice and bright.

I calibrated the system from the center seat behind the projector. Well, when watching the movie I sat off center and the image always appear blueish. I complained to my wife on the other end of the couch and she couldn't see it. Well after a few complaits I moved to her spot and the image had a slight red tint.

You will get color shifts.


clopez
 

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One thing that is important with glasbreads (or high Power) and other retroreflective screens: The CAN ONLY BE USED WITH A TABLEMOUNTED PROJECTOR . This has everything to do with the way such a screen is designed. It collects the lightrays and sends it back exactly in the same angle as they hit the screen . Your optimal viewing position when using a ceiling mount would be hanging from the ceiling. I use mine with a tablemounted crt and have no colorshift with moderate viewing angles.

I did a test with a refelective sample (cinemavision) sticked onto the screen

The result was that I had terrible colorshifting on the sample, not on the highpower. The shifting was less noticable when I stood up to emulate a sort of ceiling mounted position (angle of incidence=angle of reflection). It was very bad when I viewed from a seated position

Conlusion: never use cinemavision with a tablemounted crt.
 
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