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  1. #1
    Sirius Glass's Avatar
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    Which size/type lightbulb behind red filter for a safelight?

    I have converted my bathroom to a part-time darkroom. I removed the 75 watt bulb ceiling light that turns on with the fan. I am having a dark red piece of Plexiglas cut to fit into the ceiling fixture.

    Two questions:
    1. The Plexiglas that is being cut is not a safelight filter but it is very close to the color and density of the 8" x 10" safelight filter from FreeStyle. Is this good enough or will I have to have the safelight filter cut down?
    2. What should I replace the 75 watt bulb with: a 15 watt bulb, a 25 watt bulb or a CFL bulb [if so, what size?]? This fixture is not directly over the chemical trays, but it is about 4 to 6 feet away.
    Note: The plastic company does not want to cut plastic that they unfamiliar with. They are charging $6 for their plastic cut to size. If their "filter" does not work, then I think I can get them to cut the 8" x 10" filter down.

    Thoughts?

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

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    I leave the digital work for the urologists and proctologists.

  2. #2
    JBrunner's Avatar
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    Easiest is to take a sheet of paper out in the dark, safeguard your paper stash, and then set the paper on your work area with an object on it, a few coins, or maybe a ceramic elephant. After a few minutes process the paper and see if you get an outline. That way you can experiment with different bulbs. The CFL is likely very high in blue and green outputs, but who knows? If the plex isn't red enough, you can add some red gel.

  3. #3
    Snapshot's Avatar
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    You can probably get away with the red plexiglass, although I would advise that you test it first. There are a number of ways to do so and you can find them using the APUG search tool. Replace your 75 watt bulb with a 15 watt bulb but not a CFL version.
    "The secret to life is to keep your mind full and your bowels empty. Unfortunately, the converse is true for most people."

  4. #4
    Sirius Glass's Avatar
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    Quote Originally Posted by JBrunner View Post
    Easiest is to take a sheet of paper out in the dark, safeguard your paper stash, and then set the paper on your work area with an object on it, a few coins, or maybe a ceramic elephant. After a few minutes process the paper and see if you get an outline. That way you can experiment with different bulbs. The CFL is likely very high in blue and green outputs, but who knows? If the plex isn't red enough, you can add some red gel.
    That is my plan, I was hoping someone here might have gone through this process.

    Thanks,

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  5. #5
    JBrunner's Avatar
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    Quote Originally Posted by Sirius Glass View Post
    That is my plan, I was hoping someone here might have gone through this process.

    Thanks,

    Steve
    I have been through it, but there is no way to know if we are using the same stuff. After going through all the machinations on one light, I just purchases safelight bulbs for the other fixtures. ( Which are just the clip up spun aluminium lamps, my darkrooms pretty big)
    Last edited by JBrunner; 12-29-2007 at 02:10 PM. Click to view previous post history. Reason: changes an ef to a jee

  6. #6
    Sirius Glass's Avatar
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    My first thought was to buy a safelight bulb, but FreeStyle only had a tiny, dim bulb [7 watts]. The salesperson told me that the red coating would slowly melt off in the fixture canister. He also told me that the red bulbs sold in hardware stores were great for fogging paper.

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  7. #7
    Sirius Glass's Avatar
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    Quote Originally Posted by Snapshot View Post
    You can probably get away with the red plexiglass, although I would advise that you test it first. There are a number of ways to do so and you can find them using the APUG search tool. Replace your 75 watt bulb with a 15 watt bulb but not a CFL version.
    Thanks, I will get one this afternoon.

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  8. #8
    CBG
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    Another couple of thoughts, if you get a little fog but are most of the way there by using the red plastic. 1. put a deep red theatrical gel behind the red plastic, 2. replace the regular bulb with a red bulb in addition to your red plastic.

    Check www.rosco.com for gels, and any hardware store for colored lamps. Keep the wattage down regardless.

    Theatrical gels are pretty tough, designed to work with high powered stage lighting, but in a totally enclosed space you want to be very conservative about heat build up.

    C

  9. #9

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    As JBrunner suggests, the only way to be sure if your safelight is safe is to do a test on it. This is true whether you use a "generic" red plastic filter, as you're attempting, or if you use a conventional safelight. Even "real" safelights can fog paper if they're the wrong type for your paper, if they're too close to the paper, or if the paper is exposed to the safelight for too long.

    In addition to the options you're considering, you might consider a red or amber LED bulb. You can find several at http://www.superbrightleds.com. I use one of their red E27-R24 bulbs as one of my two safelights, and it works well for me. This particular bulb screws into a normal Edison bulb base, so you don't need a special fixture.

    In theory, a CFL might work as a safelight, if it's properly filtered; however, CFL bulbs are generally designed to replace 60-120 watt tungsten bulbs, and so are likely to be too bright unless they're kept very far from your paper.

  10. #10

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    That tiny 7W bulb puts out plenty of usable light in a small darkroom & I doubt that the coating will "melt" off. It may scratch off from handling. If it's a standard base it could be the easiest & simplest choice. Screw it into the socket & yer done.
    Heavily sedated for your protection.

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