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  1. #11

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    I'm using the red (627nm) version of these:

    http://www.lightworld.com/optiled/index.asp?id=4

    Narrow spectrum, very bright and no fogging even with VC papers. They screw into a standard socket, consume only 2.5W and are rated to last 35,000 hours.

  2. #12
    gainer's Avatar
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    I doubt that you could use amber LED's with VC paper, as it has yellow sensitivity, but I have been using red ones for years. You should test, of course, but I doubt that you will find a visibly red LED that fogs VC paper. If you want to do development by inspection of panchromatic film, use green LED's attenuated so you can just barely see by their light after you are dark adapted. BTW, red light least interferes with dark adaptation. If you want to do other things while film is in a closed tank and then inspect progress of development, use red light while working then switch to green for inspection.
    Gadget Gainer

  3. #13
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    this is probably a stupid question but just how bright are those led lights? Do they compare to a thomas safelight type brightness?

    and Sal how would you describe the brightness of that 35,000 hour bulb you recommend?

    I have for years used red christmas lights screwed into little night light units that plug into a regular wall plug. According to my testing they don't fog any kind of paper at all even at a distance of 3 feet. Very cheap and easy. A little dim though. I am very used to working in dim light so it is fine.

  4. #14

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    Quote Originally Posted by brucej View Post
    There are a number of red LED's on the market now I have been wondering if anybody has tried them as a general purpose safe light ?
    It depends on the exact spectrum emitted, which I don't know. My first darkroom experience was with a fairly bright red bulb (in a rental place) and I hwas having a horrible time getting my test strips consistent with my real exposures until I noticed that my safelight was actually not very safe at all, and that it would have an effect on the paper after maybe a minute of exposure. Obviously this was unacceptable so I switched safelights and suddenly darkroom work became a lot easier and my exposures weren't all over the map

    The simple solution is to buy one and test it. Put a quarter on a piece of paper (to make a circular shadow) and shine the red LED on it for a few minutes. If you see the outline your LED is no good, though you might be able to buy the right kind of red filter to put over the LEDs and restrict the spectrum.
    The universe is a haunted house. -Coil
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  5. #15
    dpurdy's Avatar
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    I jsut called the place that Sal recommended and asked about that led and the salesman told me it would be about the same brightness as a christmas tree bulb. so if that is the case I will stick with the xmas tree bulbs as they are very cheap and easy and don't fog the papers I use.

  6. #16

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    Quote Originally Posted by dpurdy View Post
    this is probably a stupid question but just how bright are those led lights? Do they compare to a thomas safelight type brightness?

    and Sal how would you describe the brightness of that 35,000 hour bulb you recommend?

    I have for years used red christmas lights screwed into little night light units that plug into a regular wall plug. According to my testing they don't fog any kind of paper at all even at a distance of 3 feet. Very cheap and easy. A little dim though. I am very used to working in dim light so it is fine.
    Better dim than too strong.

    I work in a tiny space (one rental darkroom closet unit just off of a big common wet sink area) and I moved my safelight to the very "back" of the room behind me. I shadow the paper while I'm working (though tests show my safelight is perfectly safe), and as a bonus this lets me read the dichroic filter setting dials on the colour head to dial in grade filtration under safe light, which was impossible when I had the safelight in front of me mounted above the wall behind the enlarger.
    The universe is a haunted house. -Coil
    .

  7. #17

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    You might need a filter and sand paper it too, just because most leds beam is so narrow that it's more useful in a flashlight than in a general light device.

    I recently made a 60 LED 940nm 'safelight' for working in the darkroom with the infrared gogles, and it works best with a piece of ground glass in front to diffuse the light to a wider angle.

  8. #18
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    I made a RED LED safelight several years ago using a single 1 Watt Red Lumiled (www.luxeon.com), a resistor and a surplus wall wart. Bounced off the ceiling, it easily makes a 11x13 foot room bright enough to easily read in, while not fogging Ilford MG paper for at least 10 minutes (the limit of my testing - the paper did not fog).

    With this light, my darkroom is considerably brighter than the one at a local school that uses the orange mercury vapor lights. I do prefer the orange light to the red, but this quick hack has worked so well that I've never gotten around to testing Amber LED's.

    The LED resistor calculator website listed above would work well for anyone doing the same. High power LEDs will get warm, so I used a version of the LED that came mounted on a small star shaped circuit board. That board and the resistor got fastened down to a larger piece of a copper PCB, and it's been running well, warm but not uncomfortable to touch. The LED is rated for a current of 350mA, but I run it at about 300mA.
    Jonathan
    -----------------------------------------------

  9. #19
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    This is an overlay of the sensitivity curve of Ilford MG-IV with the amber LED emission spectrum (the blue curve) I've been using with that paper. The horizontal wavelength scale is matched. No attempt was made to correlate the vertical intensity/sensitivity scales. You can see that the paper sensitivity is rapidly heading toward zero as it approaches the output of the LED. You should, of course, test. But I find no fogging at very comfortable lighting levels and times for me with this combination. Note that there are different peak outputs for amber LEDs, mostly between 580 and 595 nm. Staying nearer the high end of that range is probably better.

    I did find the Thomas safelight to fog relatively quickly when I was using it in a lab with Kodak Poly RC-III. I had to close the vanes completely in a very large darkroom with high, dark ceilings. The person working that darkroom before me must never have produced a really clean white. Of course no one is using that combo much these days. Many of my musings are solely of historical interest.

    Lee
    Last edited by Lee L; 05-13-2008 at 11:40 AM. Click to view previous post history.

  10. #20

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    Just to add my experience, I'm using the red E27-R24 bulb from http://www.superbrightleds.com as one of my safelights and I have no problems. The bulb is mounted in a much older safelight housing that I bought used, but I've removed the filter from the safelight housing. The result is much brighter than the light the safelight used to produce with a tungsten bulb, but it doesn't fog my paper. (I did a safelight test out to 5 minutes, IIRC.)

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