Projecting through Glass or Plexiglass??

Discussion in 'Archived Threads 2001-2004' started by Greg Miles, Apr 18, 2002.

  1. Greg Miles

    Greg Miles Extra

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    Gang,

    I'm building a projector box (with proper cooling of course)and was going to project through glass...but I have some 1/2" plexi. Will this distort the image? Will glass distort the image for that matter..

    Any recommedations are greatly appreciated.
     
  2. Deane Johnson

    Deane Johnson Supporting Actor

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    Regular glass has a greenish tint and I personally would stay away from it. Plexiglas is much, much clearer. I might question the use the 1/2" thick stuff you have on hand. I'd rather have something thinner.

    Some will point you towards some very thin optical type glass from Edmund Scientific, but I have no experience with it so can't comment.

    Deane
     
  3. DaveF

    DaveF Moderator
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    Short answer: no (aside from possible coloration problems, Deane mentioned).

    Long answer: imaging though glass plate introduces spherical aberration. However, the longer the image distance (distance from lens to scree), the lesser the image distortion. In the case of of a FPTV, you're projecting 10-20 feet, and the image is fairly low resolution image. I would expect that the glass plate would not cause any perceptible problems.

    The real killer for projection is keystone.
     
  4. Paul_Saul

    Paul_Saul Stunt Coordinator

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    Tech Spec™ High Efficiency Anti-Reflection Coated Windows
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    These glass windows are coated on both sides with a Clear Display Anti-Reflection coating (CDAR™), reducing reflectance to less than 0.5%. Back reflections are virtually eliminated by the coating, so these windows offer improved readability when used in industrial displays or computer monitors. Their high transmission makes them ideal for many other optical applications.
    Follow this link:
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    Prices range from about $15 to $50 (US) depending on the size you get.
     
  5. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    Greg,

    What kind of projector are you using? You may want to use a camera filter for the front glass, depending on the projector.
     
  6. Greg Miles

    Greg Miles Extra

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    Hitachi CP-SX5500W
     
  7. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    Wow, excellent choice!
    Is yours one of the newer ones with the purple tinge fixed?
    I believe the 5500 suffers from a bit of a cold image (too much blue). Here's some info:
    Hitachi 5500 purple/black test
     

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