12' ceiling and keystoning (help)

Discussion in 'Archived Threads 2001-2004' started by Neil Joseph, Dec 4, 2002.

  1. Neil Joseph

    Neil Joseph Lead Actor

    Jan 16, 1998
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    Neil Joseph
    I just want to bounce this off of you guys, advice is welcome because I need it.

    In 2 weeks I will be moving and setting up the new HT room. I have done all the video and audio pre-wiring already and will be setting the projector (Sony 11HT) 12.5ft away from the front wall. The challenge here is the ceiling which is 12' high (144"). The screen I will be using is a Stewart Firehawk 92" which is 45" x 80" without the 3" border accounted for, or 51" x 86" with the border.

    My dilemma here is how high to mount the screen from the floor, how long of an extension pole to use for the projector mount, and how much keystoning correction I should use. (My initial thought was to mount the screen 40" off the ground)...

    The two exteremes are as follows....

    1- Use no keystone correction but resort to an extension pole of 56-60" (very long pole/mount).

    2- Use maximum keystone correction and end up with a much shorter mount/pole for the projector.

    Of course, I could also play around with the third variable which is the screen height.

    What are your thoughts on this...

    Thanks in advance.
  2. Cees Alons

    Cees Alons Moderator

    Jul 31, 1997
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    Cees Alons

    At the moment I'm planning my HT room and I have an identical dilemma. My room is a bit lower (127"), but the problem is identical.

    Here's where I'm at the moment:
    Not all projectors do a good job in keystone corrections. Some (generally older ones) even expect to be lined up to the middle of the screen, most newer can be either placed at the ground line, or (upside down) at the topline of the screen. Some have real keystone correction, but of course it's always limited to a certain extend.
    If the 11HT has the same characteristics as my Sony 400W (and I think it does), then you need to bring the projector at the top line of the image. This could also be helped by placing the screen a little higher (or lower, whatever is needed). If the 11HT doesn't have that constraint (or 'preference') you have more freedom.

    There are other projectors, e.g. the new Sim2 300H, with bigger keystone possibilities, but the limitation may be the screen characteristics.

    Therefore, my personal choice would always be as much in front as possible, because those Firehawk screens reflect mostly perpendicularly - angles less than approx. 30 degrees (that's the trick of those screens). Exactly at the height of the upper boundary of the screen would be fine, IMO.

    Hope this helps!


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