Keystone

Discussion in 'Projectors, Screens & Video Processors' started by Frankeh, Oct 6, 2005.

  1. Frankeh

    Frankeh
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    When I project my image my width above the picture is 74"
    under the picture is 72.8"

    my screen itself is 72.8" width so I lose a bit of my picture.. I tried keystone and I can reduce the width above my picture to the same 72.8"

    though, I know you actually lose your pixels too with Keystone.. so how can I solve this problem, to get 72.8" above and under the picture?

    my Projector itself is mounted in the middle of my room, though the lense of the Sanyo Z3 isn't in the middle of the PJ so the lense isn't in the middle of the room

    To solve this I need to put the lense in the middle of the room right? I just like to know this before I take the effort in changing the ceiling setup
     
  2. Mark_a

    Mark_a
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    As long as the lens is pointing in a perfectly perpendicular line (both vertically and horizontally) to the screen, then it's only a matter of moving the picture with the lens shift wheels till it's centred on the screen. You shouldn't need keyhole adjustment at all. Though I know that's a lot easier to say then to achieve. I used bits of string to line the screen up to be perpendicular to the centre line of the room, and it hangs straight down from the ceiling so I don't have to worry about the back wall being tilted or anything.

    Regards

    Mark
     
  3. Menace

    Menace
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    You have to make you projector slightly higher as it is pointing up (torwards ceiling). I know its easier said than done, either that or point in down a bit (depends on how much sreen is left). 3rd option is keystone, but.....as you already know about pixel distortion there is really no need to go into that.
    When you point the PJ directly at the wall you will get a square image. Point it lower or higher will make the image horizontal trapazoidal. Left and right will do the same but on the verticle plains
    Mark is right about having the projector 100% perpendicular with the screen, otherwise you image will be bigger on 1 side, smaller on the other.
    Hope this helps :rolleyes:
     
  4. Frankeh

    Frankeh
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    Ok I have been trying some things... without a real solution.

    my problem is: the height of my screen left and right is 103.4 cm (I'm not using feets or inches because it actually doesn't matter)
    the width above the picture is 183.1 cm and under the picture 184.7 cm

    my screen meassurements are --> height: 104cm and width 150cm
    the height on the far left and far right are the same.. so when I make my screen bigger with the lense lever that will make no problem.. it's the width that is making a problem.

    the difference between the 2 widths (above & under the picture) is 1.6 cm (= 184.7 - 183.1)
    I tried to solve this by putting the PJ more to the ground.. (= lense height more equivalent to the screen height) [my screen is hanging 70cm above the ground]

    the height meassures became smaller but they were still the same.. the width meassures changed too.. but the difference between them stayed at 1.6cm

    so my question is.. what do I have to do to make the difference between my width (above and under the picture) as close as possible so I lose as minimum pixels as possible?

    Putting the lense more to the right/left? (as in: the lense has to be in the middle of my screen?) because when I use my horizontal lense shift to the extreme right or extreme left my width difference stayed at 1.6cm

    I hope you guys can help me.. sorry for my bad english and I hope you understand all of the above!
     

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