Screen gain cannot disobey the laws of physics,...right? - AVS Forum
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post #1 of 10 Old 04-12-2012, 03:45 PM - Thread Starter
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Screen gain cannot disobey the laws of physics,...right?

I am interested in rear projection home theater only, but I believe the rules of screen gain apply to all screens. A screen cannot produce light, only reflect it or pass it through, as in rear projection screens. Vutec claims to have a rear projection screen called the Fusion HD, that claims a wide viewing angle plus a screen gain of 2, which is very high. In order to get gain, you must restrict the viewing angle to concentrate the light in a more narrow field of view. The Vutec tech guy I spoke to also claimed that their new front projection screens that had a gain of 6 had very wide angle viewing capabilities.

What is going on here? Is this the Twilight Zone? Is there something I am missing or not understanding about the phenomena of screen gain?
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post #2 of 10 Old 04-12-2012, 05:18 PM
 
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There are different ways to measure gain. Gain is measured against a white reference close to the consistency of chalk. So if something is 'whiter' or more reflective than chalk it will be a higher gain and still maintain a good viewing angle. Add a coating and you will get an even higher gain. Whenever you add a coating to reflect more light back to a given area you will reduce the viewing area.

There is no denying physics but there is more than one way to skin a cat, and it can also depend on what is used as a reference. Use a flat black screen as a reference and a basic white screen will have lots of gain. Just to be clear Vutec doesn't do this but I mention it for demonstration only.
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post #3 of 10 Old 04-12-2012, 05:52 PM - Thread Starter
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DNP produces a Zenith screen that they claim has a gain of 2.2, but they also publish charts that show they get that gain by limiting vertical dispersion tremendously. Stewart no longer produces any screen with a gain higher than 1.5 because going higher results in a narrow viewing angle.

So how can Vutec get gains of 2 to 6 without narrowing the viewing angle, but other companies cannot? Vutec publishes no viewing angle charts or detailed information. Is this a result of obfuscation and marketing technique at the expense of honesty?
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post #4 of 10 Old 04-12-2012, 07:14 PM
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Quote:
Originally Posted by inky blacks View Post

DNP produces a Zenith screen that they claim has a gain of 2.2, but they also publish charts that show they get that gain by limiting vertical dispersion tremendously. Stewart no longer produces any screen with a gain higher than 1.5 because going higher results in a narrow viewing angle.

So how can Vutec get gains of 2 to 6 without narrowing the viewing angle, but other companies cannot? Vutec publishes no viewing angle charts or detailed information. Is this a result of obfuscation and marketing technique at the expense of honesty?

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post #5 of 10 Old 04-12-2012, 08:09 PM
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What is the gain at 30, 45 and 60 degrees? It may have a gain of .7 at 60 degrees and they could still say it has a wide viewing angle.

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post #6 of 10 Old 04-12-2012, 09:14 PM
 
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Stewart also has the 5D and Snomatte 200 which are more than 1.5 gain. The Vutec does have a narrower viewing angle, much beyond 30 degrees it is less than 1.0 gain. Tryg shows some pictures in his review.
http://www.avsforum.com/avs-vb/showthread.php?t=228371

Some gain screens do sacrifice a vertical viewing area for a larger horizontal viewing area or vice versa.
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post #7 of 10 Old 04-13-2012, 12:31 PM - Thread Starter
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I should have clarified my statement. Stewart no long makes any rear projection screens with a gain higher than 1.5.
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post #8 of 10 Old 04-13-2012, 01:43 PM
 
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Sorry, forgot you were looking at rear projection screens. I haven't used the Fusion HD, mostly Stewart and sometimes Da-lite for rear projection. You are correct about not being able to deny physics. Just like they say their Silverstar is 6.0 gain and has a wide viewing angle. It does have a wide viewing angle it is just not full gain off angle, as the angle increases the gain decreases. I'm guessing the Fusion HD is similar.
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post #9 of 10 Old 04-13-2012, 03:47 PM - Thread Starter
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What good is a wide viewing angle if the screen is too dark to enjoy watching?
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post #10 of 10 Old 04-14-2012, 05:00 AM
 
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I agree, if you need a wider viewing angle for a large screen you are better fighting it with more lumens. What are you trying to do with your HT? Screen size? Projector? How wide of a viewing area do you need?

You might not need as much gain as you think if you can control the light and conditions behind the screen, and use the right right screen material.
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