Perforated Screen pattern effect

Discussion in 'Projectors, Screens & Video Processors' started by olivier21, Mar 10, 2006.

  1. olivier21

    olivier21
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Perforated Screen pattern effect

    I have a question regarding perforated screen when using a LCD projector.
    My Sony VPL-HS51A LCD projector throw distance from the screen to the lens is 198 inches and the heights
    of the projector is 75 inches, projecting on a Dalite high contrast cinema contour perforated 106 inches.
    Right now I am using the component output via DVD player and using the AVIA calibration DVD for this test.

    Since my screen is perforated the projected image has horizontal stripes patterns across the entire screen.
    Some of you may think it's screen doors effect but it is not. After putting a large piece of white paper over
    the perforated screen the lines disappear when I focus my lens to the sharpest point.
    I can reduce the amount of the lines by changing my focus so the lines start to disappear but my picture get softer.
    Sony claims that if you are using an uneven surface, stripes pattern may rarely appear on the screen.
    So my question to all of you is how can I get a clear and sharp picture without changing my screen.

    Please find a link to my home theater with a sample picture of the perforated screen effect.
    http://gallery.avsforum.com/showgallery.php?cat=500&ppuser=7535598

    Thank you very much


    Olivier21
     
  2. PJTX100

    PJTX100
    Well-known Member

    Joined:
    Dec 21, 2004
    Messages:
    8,144
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +564
    Nice setup. Yes, a bad case of horizontal banding you have there. This "moire" effect I believe it is called is also discussed just a few threads down.

    My first thought was to wonder if changing the resolution would make a difference. But of course it probably won't because the PJ is scaling the pic to its own native res no matter what?

    If you make the pic smaller do the bands disappear? If they do, and it's not that much smaller, perhaps make the black borders a bit wider?

    Or would changing the throw distance, by moving the screen or PJ, make a difference I wonder? But again, if the pic is being zoomed to the borders this may not make a difference.
     
  3. olivier21

    olivier21
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    First of all thank you very much for your answers.

    Over the week-end I tried to find the so called "sweet spot" by moving my entire PJ base 16 inches foward and lower it. But no luck the horizontal lines patterns were there no matter what I did. I even tried to put the PJ on the floor but it was the same.

    This is my first LCD projector and in a couple of years I would like to upgrade to LCOS so hopefully the problem will not come back. In the mean time I will defocus the picture just enough so I don't see the lines.

    Thanks again for your help again.

    Olivier21
     

Share This Page

Loading...