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Join Date: Dec 2000
Location: Venice, Florida, USA
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As has been stated, the color of the screen does not have much to do with anything under discussion here. The gain of a screen is simply the multiplication process of the various gain layers the screen consists of. with a non white screen and in effect many white screens, the gain of the substrate layer is less than unity (Unity is one). Gain layers can be printed on or spayed on. The best screen material out there for a non acoustically transparent screen PQ wise is in my opinion Stewart Snomatt 100. The substrate material for this screen is just under 1.0 and a very tiny amount of gain material is sprayed on this fabric to bring it up to one. Even for this material, a minimum throw distance should be about 1.25. For screen like Studeotec130, the sprayed on gain is about 1.3 and a throw minimum is 1.3. more is better. For screen materials where the substrate material is substantially less than 1.0, the final gain divided by the substrate gain will closely approximate the sprayed on gain. The sprayed on gain will represent the minimum throw multiplier. let's take Firehawk G3 or LS. The final gain is about 1.25 and the substrate gain is about. 0.8. conservatively, a minimum throw for this material is 1.6. the new firehawk has a gain of 1.1 and starts with a 0.8 gain substrate. Conservatively this gives a minimum throw multiplier of 1.4.
Why is any of this? It has to do with the angle of the light coming from the projector lens and hitting the screen. this angle is not constant of course but depends on a variety of factors. The longer the throw multiplier one uses for set up, the less the worst case angle will be. In olden days, commercial theaters were much longer than they were wide and the projector was mounted in the rear. High gain screens were and are still used. No problem with long throws.
For home use, err on the long side to minimize screen material induced artifacts.
All this of course is for angular reflective screens. Retro reflective screens, the only real example is Da-lite HP of whatever gain and rebranded uses of this material. Throw is not really relevant though this material has its own weaknesses which thankfully most don't see because they are happily blinded by the light.
The screen industry has become like the older days of speaker manufacturing. Anyone can easily enter the screen manufacturing business without knowing very much. Many screen manufacturing companies do not specify very much re the fabrics they use and recommended minimum throws.
Last edited by mark haflich; 11-26-2014 at 12:53 PM.