What Is The Distance From the Screen Are You Supposed to Install Your Projector?

Discussion in 'Displays' started by Jay Foster, Feb 1, 2006.

  1. Jay Foster

    Jay Foster Stunt Coordinator

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    I just got a BenQPE7700. I am getting a 16:9 screen between 140"-150". The BenQ manual says I can place the projector between 14.5 and 19.5 feet for a 150 inch screen. It will be mounted on the ceiling. I would prefer 19.5 as that will put the projector almost above my head rather than in front of me.

    I looked at projectorcentral and it seems to say something different. Can someone give me an idea of where it is supposed to be?
     
  2. Jay Foster

    Jay Foster Stunt Coordinator

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    Anyone?
     
  3. Alex Antin

    Alex Antin Extra

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    Keep in mind that the farther away from the screen...the lower the light value hitting the screen. You have a variable focus lens which gives you some play but you want as much light as the projector is putting out ON the screen.
     
  4. Cameron Yee

    Cameron Yee Executive Producer
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    I think a better question may be where you should be sitting given the size of your screen, though at that size I would also be concerned about light fall off affecting the brightness of the image.

    Generally with 720p projectors people sit at a distance of 1.5X the screen width. With a 150" screen, you would be sitting around 16.5' feet away, so the projector would actually be behind you if you don't use the zoom (which most try not to do). I'm also basing this on the Project Central calculator for that model projector.
     
  5. Jay Foster

    Jay Foster Stunt Coordinator

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    Got it. Now I understand better.
     
  6. ChrisWiggles

    ChrisWiggles Producer

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    Gah. nonono. Not true! The projector has variable zoom, so it will remain the same. There can be some small differences in light output based on the zoom position of the lens, but this is optical loss in the lens system, and has nothing to do with the distance of the projector to the screen.
     
  7. Jay Foster

    Jay Foster Stunt Coordinator

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    Chris,

    Does it matter then where I sit? Can I locate the projector at 19.5 feet on the ceiling?
     
  8. ChrisWiggles

    ChrisWiggles Producer

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    If that's within the specified zoom range for your projector at the screen size you want, it should be just fine. That seems to be what your manual says (according to you), it also is the same thin the projectorcentral throw distance calculator predicts at the min zoom setting.

    That is a fairly large screen, so it may be dimmer than you want to go that big unless you go with a high-gain screen, but that's user preference.

    At 19.5 feet, you can have a 16:9 diagonal size from abotu 150" to 204" depending on lens zoom setting. Those are pretty large screen sizes.

    As for does it matter where you sit, I don't know what you mean by that question?
     
  9. Cameron Yee

    Cameron Yee Executive Producer
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    I believe he's referring to the 1.5X screen width guideline I mentioned above. I'll let you explain that one [​IMG].
     
  10. ChrisWiggles

    ChrisWiggles Producer

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    This is a 720 DLP projector, so how far away you want to be really depends on how much you are bothered by screen door. I am a CRTer, so I really prefer a smooth picture, and I don't like to sit closer than 2x screen widths because I see SDE effects which bother me.
     
  11. Jay Foster

    Jay Foster Stunt Coordinator

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    Looking at a Draper screen. I have to find out the gain on it.

    According to Draper's website it is a 1.0 for the gain.
     

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