All Screen Gain Calculator - Page 2 - AVS Forum
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post #31 of 46 Old 01-19-2010, 12:58 AM
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This is the coolest calculator I've ever used!
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post #32 of 46 Old 01-21-2010, 07:26 AM - Thread Starter
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Quote:
Originally Posted by curt248 View Post

This is the coolest calculator I've ever used!

Thanks! Personally, I think the coolest part of the calculator is the use of 3-D vector math to solve for the error angle. I needed a general solution that would allow the projector, the screen, and the viewer to be placed ANYWHERE. Special 2-D cases, such as having the projector and viewer centered on the screen with the projector directly above the viewer, can be solved with simple trigonometry. The general 3-D case, however, had me stumped until I discovered the 3-D vector math tutorial referenced in post #6 of this thread. The 3-D vector math provided the elegant and easily implemented solution I was seeking.
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post #33 of 46 Old 01-21-2010, 09:05 AM
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Wow. There has been a lot of people saying that their 8500 has had a serious problem. Anyone find out how common these type of problems are yet?

Is there a solution for the consumer? The other pj I was considering was the panny ae-4000. I have since taken that pj off my list due to lower lumen output.

Do all pj's have serious problems? The panasonic warranty requires you to bring the unit to the shop or send it in without having a replacement. With the rate that these things have problems that seems to be an unacceptable solution. No pj for weeks or months while they figure out if they think you have a problem with it?

It's no wonder that epson doesn't have any 8500's for sale on their website. They may have had to send out every unit for warranty replacements.

Do the JVC's have this many problems? What is their return policy?

Is a used pj ever a valid option considering the amount of people that have problems?
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post #34 of 46 Old 01-21-2010, 10:44 AM - Thread Starter
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Since I just bought an RS10 about 6 months ago, I haven't been keeping track of what's happening recently in the projector forums. No problems yet with my JVC. Concerning returns, you should buy from a reputable dealer, such as AV Science (the forum owner). They will also QC the PJ for a slight extra charge. You might get a lot more responses to your questions over in one of the projector forums though, rather than here in the screens forum.

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post #35 of 46 Old 01-24-2010, 03:17 PM
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FLBoy >>> I noticed on this thread that you repeatedly informed people of the importance (necessity, even !) of placing the projector facing the center screen when using a Da-Lite High Power screen.
What if the projector must be located with the lens facing the bottom or the top of the screen, at the screen's exact mid-point ?
Would i not get the specified gain of 2.8 when mounting it so ?
Thanks >>> Marcos
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post #36 of 46 Old 01-24-2010, 04:48 PM - Thread Starter
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It is important that the PJ is centered horizontally on the screen, or the viewers will get different gains on different sides of the room. It is NOT important that the PJ is centered vertically on the screen, as long as the viewers eyes are relatively near the PJ lens. Moving the screen up or down a foot or two will make little difference.

BTW- You won't get a usable 2.8 no matter what you do, because either the PJ would be blocking your view, or you would be blocking its view of the screen. A gain of about 2.4 is the best you can do in any practicable installation (unless you want to wear the PJ as a hat).
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post #37 of 46 Old 02-26-2010, 07:36 PM
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Great tool!!

Thanks

Daniel

JVC RS-10
Sony KDL-46S5100
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post #38 of 46 Old 02-26-2010, 08:25 PM
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We currently have our pj mounted a few feet to the left side of the center of the screen. We just sit towards the left side and get great gain with our da lite 2.8. This screen looks good at any angle to be honest. It is a bit brighter when seated near the lens though. It would be totally viewable at extreme angles which by using the screen gain calculators would be gain 1 or a bit below that. If you punch in the calculator for other popular screens with a gain rating of 1.4 (like the stewarts) you still end up with similar (~1 or a bit less) at the same extreme angles. I'm not sure what you might gain (pardon the pun) with using a 1.4 screen for anything.

At best the 2.8 da lite looks much brighter than others and at worst it looks about the same brightness as others.
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post #39 of 46 Old 02-27-2010, 06:42 AM - Thread Starter
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Quote:
Originally Posted by curt248 View Post

I'm not sure what you might gain (pardon the pun) with using a 1.4 screen for anything.

I'm not sure either. That's why the High Power is the one and only screen I have ever owned, and I'm not looking to trade anytime soon.

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post #40 of 46 Old 10-14-2010, 01:44 PM
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Flboy,

I have been going back and forth with your calculator to get the highest gain I can of the Da-Lite HP screen and need some help. There are some items that cannot change at all. My inputs are listed below (* cannot be changed)

Screen width will be 113"*
Center of screen will be 68" (bottom of screen is 36" AFF)*
Viewing distance is 17' (204")*
Distance to left or right of projector - 36"*
Center of lens from floor - 68"
Viewing eyes height is 37"*

When I have all of this before inputing the distance from left to right it shows a gain of 2.02. But after this is it reduces both left and right to 1.52 gain. With this low of a gain the HP may not be the screen for my setup. But if I lower the PJ 60" AFF it increases the gain to 1.65 and at 55" it is up to 1.71. But this is still a long way from the gain of 2.02 before the left and right distances are imputed.
n
The key question is why does the seating left and right change the gain so much. Obviously everyone cannot sit directly under the PJ. Is this correct? The other key question is I thought the projector being in the center of the screen was one of the key ingredients for higher gain.

If everything is correct then the only option I have is to have the PJ lower than the center of the screen. I will be ceiling mounting the projector and already have an extension pole for this - so I can lower it some. The PJ will be over a table that is between the two chairs.

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post #41 of 46 Old 10-26-2010, 08:49 AM - Thread Starter
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For anyone who may be interested, I have posted the screen parameters for the 2.4 gain High Power screen in post #2 of this thread.

rgathright: The reason the gain decreases at the side viewing positions is that it is the total (three-dimensional) angle between the projector beam and the viewer's line of site to a point on the screen which counts. This is fully explained in post #6 of this thread.

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post #42 of 46 Old 04-05-2011, 11:45 PM
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Im looking at the DaLite HP 2.4 SCREEN. The Projector will be 14.5 feet from the screen. The screen will be around 46 x 108 2.35 apspect ratio. The projector is shelf mounted 10 inches above center of screen viewing area. Will this be ok. I am not very smart when it comes to this type of stuff. I appreciate anyones help. Thank you in advance.
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post #43 of 46 Old 04-02-2013, 04:06 AM
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Wow! what a useful calculator. Thank you so much.
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post #44 of 46 Old 12-21-2013, 08:23 AM
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Very cool calculator
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post #45 of 46 Old 01-23-2014, 01:51 AM
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What is this used for?

Is it to figure out what is the ideal gain of the screen for your setup?

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post #46 of 46 Old 01-23-2014, 01:54 PM
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You can do that w/o the calculator, which tells you what gain you'll get for a given screen and setup (positions of viewer, screen, and pj).

Noah
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