DILA Mount/Screen Size Question for Group - AVS Forum
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post #1 of 9 Old 05-05-2001, 11:37 AM - Thread Starter
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If I have a G-15 DILA, and I want to mount it in the rear of the room, inverted, and I want a 110" Diagonal (8' wide) 16:9 Screen.

I understand that a DILA must be mounted such that the lens is equal to the top of the projected image, however, it is also my understanding that the lens is equal to what would be the top of a 4:3 image, not a 16:9 image..

So that having been said, if my screen is 24" off the floor, and it is 54" tall (16:9) what height will the lens on my DILA be ?? I assume higher than 78", correct or not??

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post #2 of 9 Old 05-05-2001, 11:43 AM
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You can use Dilard to adjust what the default "bottom" of the screen is.
So I'd align the top of the screen with the lens. You'll need Dilard for
a lot of other useful things, so you'll probably end up buying it. However
Mark Hunter lets you take it for a full featured test drive (aside from
saving the info). Just make sure the length of the room matches the throw
distance of projector. There is an image calculator for the DILA somewhere
and I used to know where it was, but since I've mounted my projector, I
haven't refered to the link in a while.

Mark

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post #3 of 9 Old 05-05-2001, 01:46 PM
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Hi Cain,
For a 4:3 image of 54" (54*96 16:9 screen)high your D-ILA will produce an image of 72 inches wide. In order to produce an image 96 inches wide the corresponding image height would have to be 72 inches. When you engage the 16:9 switch of the projector (available on the non-computer resolutions) you will lose 25% of the height of the image (12.5% above and below the screen). This will produce the same 54" height that you desire. Mount the projector with the middle of the lens at the top of the viewable part of the screen (the lens diameter is about 4"). In your situation the bottom of the lens will be 76" off the ground.

To calculate the minimum throw distance necessary to produce a certain width image , multiply the desired image width by 1.9. The lens calcuator resides here (click for a download)http://www.jvcdig.com/lensv406.exe



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post #4 of 9 Old 05-05-2001, 02:18 PM
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Cain,

Don't forget that if you plan on getting or are awaiting the Panamorph lens, you'll need to calculate in the fact that the image will be lower than the lens center. For my 15 to 16 ft. lens to screen, that'll be around 5 or 6 inches. In other words, my lens center will be 5 or 6 inches higher than normal. This was a concern with those who had their projectors already mounted on their ceilings.

Chris

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post #5 of 9 Old 05-05-2001, 03:54 PM
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Quote:
<font face="Verdana, Arial" size="2">Originally posted by CCLAY:
...the image will be lower than the lens center. </font>
Won't the Panamorph put the top of its 16:9 image at the same place that the non-Panamorphized projector defaults to having a 16:9 image?

- Dave
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post #6 of 9 Old 05-05-2001, 06:39 PM
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Not if I remember the Panamorph website instructions for mounting. It will place the top of the compressed image 0.048 x throw distance below the normal top of the 4:3 image.

Now -- coincidentally(?) -- if you were to use a 96"=8' wide screen with a D-ILA projector and placed the projector at an even 2x width, meaning 192"=16', THEN this works out to placing the Panamorph image 9" below the top of the 4:3 image. Which is exactly where the D-ILA without a Panamorph places it when in 16:9 mode for video sources.

The website says that you can make the Panamorph image and 4:3 image hit the same height by tilting the projector upwards 3.9 degrees. That's the one I can't quite figure out. If it means tilting WHILE using the Panamorph and NOT tilting while NOT using it, then I can see it. But if a permanently tilted projector puts the image in the same spot with and without Panamorph, then I don't quite get it.

What I do know is that I've had a gaping hole in the wall between my living room and closet/projection booth for 8 months now while I've waited for this thing. One way or another, when it finally arrives, I WILL make it work.


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post #7 of 9 Old 05-06-2001, 07:35 AM
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Kirk:
I think you're right. I just checked the Cygnus web site, and, although I don't see the .048 number explicitly mentioned anywhere, I did run some numbers through their "lens calculator", and they seem to match up with what you're saying. My screen installer had thought that the lens would put the image in the same place that the projector puts the 16x9 image. With my 18' throw, and my 84" screen width, there is a difference for me of a couple inches. So, I've got to resolve this...
- Dave
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post #8 of 9 Old 05-07-2001, 09:12 PM
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Dave,

The Panamorph will lower the top of the image by about
5 inches [approx] for every 10 feet of throw.

Use the calculator on the Cygnus website to get a more
accurate estimate.

Greg

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post #9 of 9 Old 05-07-2001, 09:29 PM
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Greg:

Thanks. Yes, as Kirk said, it's .048 times the throw distance. So, to be exact, it's 5.76 inches for every 10 feet of throw.

- Dave
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