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post #1 of 7 Old 01-25-2002, 08:28 AM - Thread Starter
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Hi ALL !!

How can I determine the screen gain to be use?
Is there any specific formula for CRT,DLP an LCD?
What Is the basis? Light output(ANSI LUMENS)?
Or depends on the projector to be use?
Any Idea?:confused:
Thanks!


Edgar
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post #2 of 7 Old 01-25-2002, 09:11 AM
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Screen brightness (foot lamberts) = Projector brightness (lumens) / Screen Area (sq. feet) * Screen Gain

You should be targeting 16-22 foot lamberts if you have total light control, and more if you have ambient light in the room.

Dave.
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post #3 of 7 Old 01-25-2002, 10:32 AM
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Quote:
You should be targeting 16-22 foot lamberts if you have total light control, and more if you have ambient light in the room.
True, but 10 ftL can also be enough for a VERY good viewing experience. Otherwise I agree with David, brighter is better (up to a point that is).
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post #4 of 7 Old 01-25-2002, 02:26 PM
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I have a Barco 808s which I understand puts out about 250 ANSI lumens. According to this formula, I would need a gain of about 2.3 to get 16 ftL on an 8 foot wide 16x9 screen.

That seems kinda high. I understood that a high gain screen has some tradeoffs (color shift, host spotting, decreased viewing angle, etc..). Is there a point where these factors start to outweigh the brightness? I realize this is probably a mater of taste but is there not some general rule of thumb?
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post #5 of 7 Old 01-25-2002, 04:18 PM
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On a CRT projection system, getting above a screen gain of approximately 1.6 or so, gets you into an area where the gain consideration will intrude into the viewing experience, in my opinion. Higher gain is fine for retroreflective screens, but not for flat surface types, which are the kind we generally speak of here on the forum.

Ken Hotte

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post #6 of 7 Old 01-25-2002, 07:12 PM
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CRTs can put out much higher flux over a small area than their total lumen rating suggests. You really don't need to average 12 ft-lam over an entire screen to have a good viewing experience.

Steve
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post #7 of 7 Old 01-27-2002, 04:18 PM
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I'm not sure but I think less than a year ago we were quoting 10 foot lamberts as the low end. That may not sound like a giant difference but that 20% can really make a difference in recommended screen dimension as well in selecting a perf screen or not .
Art

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