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Thread: DIY Light Table

  1. #1
    donbga's Avatar
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    DIY Light Table

    I'm not sure if this is the best forum to post this question but does anyone know of any sources for building a light box roughly 3x4 feet in dimension?

    Don Bryant

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    "Build your own home darkroom" by Lista Duren and Billy McDonald.

    They have a diagram for a 2x3 box, but I dont see why you cannot adjust the size to fit your needs.

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    glbeas's Avatar
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    Light boxes, or light tables as graphic art folks call them are easy to build. Easiest one I ever built was onto a folding table. I built a box on top with 1x12s and used trim to make a ledge around the inside deep enough for a sheet of glass and a sheet of translucent plexi stacked. A couple of twin bulb flourescent fixtures are laid on thier backs inside wired together to an external switch. If the glass is very large a support rod should be put in the center, a threaded rod with nuts and flat washers in a hole on the table and the other end with a rubber tip capping it and adjusted to be level with the trim ledge. The inside may be painted white to even the illumination. Some folks even build a door into the side of the box to make it easy to change the bulbs out.
    It's not much different from a uv contact print box.
    Gary Beasley

  4. #4
    donbga's Avatar
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    If the glass is very large a support rod should be put in the center,.
    A thicker sheet of plate would be better, the shadow of the rod would be totally unacceptable.

    Some folks even build a door into the side of the box to make it easy to change the bulbs out.
    I'm not sure I see the utility in that. It would be easy enough to drop the support out.

    It's not much different from a uv contact print box.
    I would say not at all like a UV printer, but thanks for the suggestions.

    Don

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    rbarker's Avatar
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    I guess my questions, Don, which I haven't seen addressed yet, are color temp, optimal spacing for evenness of illumination, and ideal level of illumination (how bright should it be?).

    If it's to be used strictly for B&W, color temp isn't much of an issue. But, for color transparencies, it would be. I'm not sure if "daylight" bulbs provide the proper color temp, or if specialized bulbs are needed, for example.
    [COLOR=SlateGray]"You can't depend on your eyes if your imagination is out of focus." -Mark Twain[/COLOR]

    Ralph Barker
    Rio Rancho, NM

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    Note, that with the new fluorescent bulbs with integrated ballast all you have to do is rig a box with sockets and just screw in a few bulbs, far easier than wiring for ballast and conectors.

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    What would be a good alternative to florescent bulbs? At some point (since, as are probably many of you, I'm always designing my next darkroom in my head) I want to have a light table recessed into a counter of my darkroom. Florescent bulbs would be a no-go, since they continue to fluoresce for a time after the power is removed presenting a danger of film/paper fogging.

    How practical would it be to put a bunch of white LEDs wired in sequence as a light source? Are LEDs expensive?

    Also, what's a good way to make a sheet of plexi evenly translucent? Sand it? Unless you own a good spray painter, I would think painting would be unevenly thick, show brush strokes and tend to yellow over time. Also sounds unnecessarily thick.

    -KwM-

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    wdemere's Avatar
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    Quote Originally Posted by kwmullet
    What would be a good alternative to florescent bulbs? At some point (since, as are probably many of you, I'm always designing my next darkroom in my head) I want to have a light table recessed into a counter of my darkroom. Florescent bulbs would be a no-go, since they continue to fluoresce for a time after the power is removed presenting a danger of film/paper fogging.

    How practical would it be to put a bunch of white LEDs wired in sequence as a light source? Are LEDs expensive?

    Also, what's a good way to make a sheet of plexi evenly translucent? Sand it? Unless you own a good spray painter, I would think painting would be unevenly thick, show brush strokes and tend to yellow over time. Also sounds unnecessarily thick.

    -KwM-

    These guys may be able to help: http://www.discreteled.com/

    They have a flashlight bulb that is all red that might be a handy darkroom tool too.

    Good luck,

    William
    "I know of no country in which there is so little independence of mind and real freedom of discussion as in America." -- Alexis de Tocqueville

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    kwmullet's Avatar
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    William,

    Thanks for the tip. I wouldn't need or want the light table to be safe when on, though. I'd only use it when I was "light". I just want it to give me a good even white light table surface, and when I turn it off and go dark to be sure it doesn't fog paper or film like florescent tubes might.

    -KwM-

  10. #10
    Craig's Avatar
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    Quote Originally Posted by kwmullet

    Also, what's a good way to make a sheet of plexi evenly translucent? Sand it? Unless you own a good spray painter, I would think painting would be unevenly thick, show brush strokes and tend to yellow over time. Also sounds unnecessarily thick.

    -KwM-
    I built a light table for a geologist friend to sperad his maps on, it was 3x5' and I used a piece of 3/8" sandblasted glass. Its strong, self supporting and when sandblasted quite uniform illumination. I put flurescent lights underneath, and had the top hinged to allow access for changing the bulbs. I can't recall the cost of the glass, but I went to a commercial glass shop and it wasn't that expensive.

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