question about projection

Discussion in 'Displays' started by firebrick, Nov 23, 2008.

  1. firebrick

    firebrick Agent

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    What kind of angle do projectors shoot their screen at. I want to use my far wall for my screen but I have a header that runs the length of the room, 5 feet from the far wall, and hangs down 12 inches. The ceiling for the rest of the room is 93" so the header hangs down at 81". I have a picture if someone needs to see it to know what I mean. I am wondering if the header will prevent me from using a projector, I dont know much about them. How far from the floor do you usually put a screen? If I didnt have to put the top of the screen near the ceiling I should be ok, right? Picture included.
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  2. Allan Jayne

    Allan Jayne Cinematographer

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    Most projectors are adjustable (using lens shift) in terms of shooting angle. They normally shoot at dead center of the screen but you can leave the projector pointing horizontally and raise or lower the image relative to the projector. (Also side to side.) Those that are not so adjustable usually aim at the bottom center. Turn these upside down to mount on or near the ceiling and aim at top center.

    No matter how adjustable the projector is, either a ceiling projector mounting or the top edge of the screen or both must hang lower than the ceiling itself in order to shoot under the header. If one is higher than 81 inches then the other must be lower than 81 inches. Hint: Stretch a string to go straight under the header. This will give the maximum height for the projector and screen.
     
  3. John Dirk

    John Dirk Second Unit

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    Just to add to what Allen said, LCD projectors generally offer much more placement flexibility than their DLP counterparts.

    John
     
  4. firebrick

    firebrick Agent

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    Where is the center of the screen supposed to be in general? Eye level with first row viewers? Or second?
     
  5. Leo Kerr

    Leo Kerr Screenwriter

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    In my experience, projectors come in two different styles. In each case, the projector is pointed "square" to the wall.

    A: the projector is in-line with the top or bottom edge of the image or within 10% of that line. Thus, if it's sitting on a coffee table, the bottom edge of the image is along the line of the coffee table, going up.

    B: the projector is in-line with the center of the image, like a good old-fashioned slide projector.

    In either case, projectors will almost certainly have either optical or electronic keystone correction, so that if the projector ISN'T square with the wall/screen, the lines can be MADE square. Optical keystone correction is a bit more expensive, and is much higher quality then electronic keystone correction. Electronic correction is a gross resampling and distortion of the image that at best will sacrifice a lot of actual resolution.

    Leo
     
  6. Jim Mcc

    Jim Mcc Producer

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    A projector will work just fine in your room. My room's ceiling height is only 80". The "rule of thumb" for screen height is for your eyes(when seated) to be about 1/3 of the way up from bottom of screen. My screen is 52" tall, and is about 28" above floor.
     
  7. SherardP

    SherardP Stunt Coordinator

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    I too agree and think you will be fine with a front PJ setup in that room. Im thinking you should break out the measuring tape, use some masking tape, and mask out the actual screen. I did this using Carada's measurements on their website for my own purchase. That should give you an idea of screen size and the size you feel will work for your room.
     

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