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  1. #1

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    Plastic "Ground Glass" Am I nuts?

    I'm starting to put together my ideas in preparation for a 4x5 monorail for field use. As part of this, I thought it may be better to use acrylic to cut down on weight however I've never seen anyone mention or do this. Is there any reason it wont work?

    Also, I forget right at the moment, is the film plane in the same position as the front (lens side) or back (viewing side) of the ground glass? - i.e. what surface needs to be in the same position?

    Thanks.

  2. #2
    Dave Parker's Avatar
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    Your not crazy, people do it, the ground side of whatever you use needs to be tword the lens and the ground side is the same as the film plane. One thing to take into account, is the amount of weight savings in this size of camera is going to be virtually nothing, as a real ground screen in this size only weighs about 4oz and a plexi screen will weigh about 3oz. In the overall scope of things, 1 oz is nothing.

    Good luck....

    Dave Parker
    Satin Snow Ground Glass

  3. #3
    smieglitz's Avatar
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    I recently replaced a broken ground glass screen of a homemade 8x10 box camera with a piece of 1/8" acrylic that is frosted on one side and smooth on the other. It worked fine and I did not notice any loss in brightness with it. I certainly will be replacing the GG of my 11x14 with the stuff at the first opportunity.

    Joe

  4. #4

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    Not nuts, no, but there is one small thing to watch out for. Plastic will flex far more than glass so don't press too hard in the middle of the screen with your loupe, or you'll be shifting the plane of focus. The bigger the format, the greater the risk, obviously.

    Cheers,

    Roger (www.rogerandfrances.com)

  5. #5
    Pragmatist's Avatar
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    As Roger & Dave point out, there is no appreciable weight savings and the plastic is not optically stable. In some cameras, the fresnel (which is plastic) achieves part of its plane characteristics by the support of the GG it lies next to. There are also issued with focus grain definition, brightness, corner falloff, etcetera. Rather than plastic, look at one of the Satin Snow GG's, or bite the big-buck-bullet and think about a Beatty interscreen. Either choice will make you happy you did...
    Patrick

    something witty and profound needs to be inserted here...

  6. #6

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    there are some weight savings for 8x10, but not really so much for 4x5 (it's also rather easier to smash an 8x10 gg...)

    plenty of info in a recent thread:

    http://www.apug.org/forums/forum44/29914-what-use-plexiglass-viewing-screen.html

    (BTW - Maxwell screens are far superior to Beatty intenscreens. You might look at one of those rather than make your own plexi-GG?)

  7. #7
    Lachlan Young's Avatar
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    Quote Originally Posted by tim atherton
    there are some weight savings for 8x10, but not really so much for 4x5 (it's also rather easier to smash an 8x10 gg...)
    Has anyone ever put their head through a gg screen?

    Lachlan
    "A squid eating dough in a polyethylene bag is fast and bulbous...got me?" Captain Beefheart

  8. #8

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    Quote Originally Posted by Lachlan Young
    Has anyone ever put their head through a gg screen?

    Lachlan
    No, but I've broken enough GGs -- from 6x9 cm to 11x14 inch over the years -- that the one reason I would consider Perspex or the like is that it's harder to break.

    Cheers,

    Roger

  9. #9
    jp80874's Avatar
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    Quote Originally Posted by Roger Hicks
    Not nuts, no,
    Roger (www.rogerandfrances.com)
    He is here isn't he? Gotta be nuts.

    John Powers

  10. #10
    jp80874's Avatar
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    Quote Originally Posted by Lachlan Young
    Has anyone ever put their head through a gg screen?

    Lachlan
    Philip is talking about a 4x5. That might be a challenging task.

    John Powers

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