What to do with a low ceiling? - AVS Forum
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post #1 of 5 Old 02-19-2002, 10:29 AM - Thread Starter
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My home theater room is about 15' x 12'. The projector is about 14-15' from the screen (a plain white wall). The ceiling is a drop ceiling, about 7' high. The wall that is used as the screen has a usable area of 44" high (the bottom portion is cedar wood, the top portion is painted sheetrock). My projector is 4x3 (panny 701u). Hopefully I'm explaining things clearly.

Anyway, I'd like to use a constant height display, but it's not that simple because of the ceiling. Here are some ideas (none of them are ideal, maybe you have better ideas?):

1. Tilt the projector so that the top of the image aligns with the top of the wall (so that no light spills onto the ceiling). Then, use an HTPC for precise aspect control and image placement (I don't believe there are any STB's that allow you to position an image, but I could be wrong). Then, I'd project 4x3 material at 56"x42", 16x9 material at 75"x42", and 2.35 material at 99"x42". As I said, my projector is 4x3, but it also has a 3x zoom. So in order to achieve the image sizes stated above, I could:

a. Build a stand for the projector where the tilt could be adjusted. This would work as follows: 16x9 (1024x576) would be aimed so the top of the image aligns with the top of the wall at standard projected size (no zoom). For 2.35 (1024x436), the projector would be tilted even lower, so that the image aligns with the top of the wall when using maximum zoom. 4x3 (768x576) would be left/right letterboxed inside of the 16x9 image (I don't watch much 4x3 material).

b. Sustain a constant tilt for the projector, based on the top of the 2.35 image aligning with the top of the wall. Then, just use fewer pixels for 16x9 and 4x3. So, 2.35 would get 1024x436, 16x9 would get 775x436, and 4x3 would get 581x436. The obvious disadvantage to this is that I would only be using a portion of all of my pixels. Since only the top portion of pixels will ever be used (the top 436), I wonder if I'd have to worry about image burn at all (I've heard mixed reports about lcd image burn).

2. Continue to project in the middle area of the projector (no tilting) and use the zoom for 2.35 vs. 16x9. Under this scenario, I would be projecting part of the "unused image" onto the ceiling (as I do in my current setup). I could then put some material onto the ceiling to absorb the light. The negative here is WAF, since it would probably look pretty bad when lights are on and the projector's not in use.

3. Purchase a screen and project the image lower (no cedar trim to deal with). The negative here is mo' money.

4. Use some other image scheme (constant width, constant area, etc). I don't think this would really solve the problem though.

Hopefully, this wasn't too confusing. Let me know if I need to clarify any of this or post it in another forum.

Thanks!

-Gene
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post #2 of 5 Old 02-20-2002, 12:45 PM
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Gene,

I'm trying to picture your scenario, and I think I can follow. I have a 7'1" ceiling height in my HT with my projector's lens (4x3 native) at a distance of approximately 13' from a 60"x80" screen (100" diagonal) in 4x3 format. IMO, opt for a screen and project all your image sizes within a 4x3 format screen. This way you can project all formats within this screen and don't have to make adjustments every time you switch formats. I don't know what your budget is like, but it'll help you enjoy your HT a little more if you don't have to fuss with adjustments all the time. Plus, your wife will like the aesthetics :D. I hope this helps!
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post #3 of 5 Old 02-21-2002, 09:17 PM
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Gene,

Although I am not that familiar with the panny 701u,
I have a similar situation, and I use the constant height configuration.

First, try to avoid tilting of any kind in order to minimize keystoning. Most Keystone correction schemes will degrade your image especially if you are trying to bypass the FP's built-in scaler.

In any case, I used Dilard (I have a ceiling mounted Dila) to top align my 2.35 and 16:9 images. The 16:9 (HD, DVD) image is optically zoomed to the middle portion of the 2.35:1 screen. 4:3 images a are projeted in middle of the 16:9 image on the 2.35:1 screen. (Equip: DiLA, E*6000, CrystalImage scaler, Tosh 5109 DVD player)

With the panny 701u, you could use an HTPC or Quadscan scaler to achieve the same effect. Just mount the FP inverted and as high as possible.

Andrew.

Life is short. Enjoy!
Andrew.
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post #4 of 5 Old 02-25-2002, 08:27 AM - Thread Starter
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vdelauz - thanks for the feedback, but a 4x3 screen would perhaps be the worst solution for my situation. I'm not sure I understand how you'd get a constant height screnario out of a 4x3 screen.

midi-guy - I'm not sure I understand. If you optically zoom the 16x9 image in the middle of the 2.35 screen, wouldn't there be excess above and below the screen? I'm trying to prevent any light spill above my "screen" (wall), since it would reflect of of my ceiling.

Thanks!

-Gene
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post #5 of 5 Old 02-26-2002, 10:36 PM
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Gene,

If your projector is properly installed, there should be no light spill - at least not onto the ceiling.

BTW, I looked up your projector on ProjectorCentral.com
The screen size calculator yields the following @ 15' screen to FP distance.

Calculated 4:3 Screen Size
Diagonal Range: 116.9 - 153.8 in. ( 9.7 - 12.8 ft.)
Height Range: 70.1 - 92.3 in. ( 5.8 - 7.7 ft.)
Width Range: 93.5 - 123.1 in. ( 7.8 - 10.3 ft.)

Calculated 16:9 Screen Size
Diagonal Range: 143.1 - 188.3 in. ( 11.9 - 15.7 ft.)
Height Range: 70.1 - 92.3 in. ( 5.8 - 7.7 ft.)
Width Range: 124.7 - 164.1 in. ( 10.4 - 13.7 ft.)


I would say you are way off vis-a-vis the desired screen size.
IMO, tilting the FP would result in acute keystoning. Have you actually tried this? You probably need to move the FP closer to the wall, i.e. 8ft from screen.

In any case, before getting my current screen, I overcame my height problem by getting a motorized 45" high 16:9 screen.
The screen was recessed into the ceiling and mounted at about 20" from the wall. (The obstruction was my equipment rack and a TV).
The screen would unroll down to about 24" above the floor - the bottom of the 16:9 image. There was a black drop of about 15" at the top of the screen.
Watching 4:3 material at the same width would have been impractical - bottom of screen would be too low, so I did not watch much 4:3 material per se. The E*6000 HD DBS receiver allows me to center a 4:3 image on 16:9 screen.

In addition to the 16:9 screen, I now have a 2.35:1 45" high screen.
See rest of description in this thread2.35 screen

Andrew.

Life is short. Enjoy!
Andrew.
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