Is green LED safelight?

Discussion in 'Darkroom Equipment' started by gma, May 10, 2005.

  1. gma

    gma Member

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    Tonight I loaded a 35mm roll of J&C Classic 400 onto the reel in my darkroom. When I was almost finished loading I noticed the glow of the green LED on my electrical power strip. The light was under my counter and less than two feet from the end of the film which was dangling near the floor. I expected that the film was ruined, but developed and discovered that the negatives are normal with not a hint of fogging. I will cover the LED with some black electrical tape next time.

    I do not recommend using green LED for a safelight, but I was lucky this time.
     
  2. josephaustin

    josephaustin Member

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    The glow in the dark timers, my Gralab and timeolite do not fog my film, I use the gralab to time my sheetfilm developing in open trays. Similar shade of light I assume would also not fog film.
     
  3. Loose Gravel

    Loose Gravel Member

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    Green is not safe; the low intensity was below threshold.
     
  4. colivet

    colivet Member

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    Led's light spectrum is really, really narrow. It can still expose film if you wanted to.

    I use those little led safety night lights to inspect film development progress. It never exposes the film, which is of course quite desensitized during development.
     
  5. 127

    127 Member

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    the trick with green is that our eyes are very sensitive to it, while panchromatic film is (roughly) equaly sensitive to all frequencies.

    For that reason green is a better safelight than red for panchromatic material - what looks bright to us is still pretty dark to the film.

    By comparason a blue light which we would hardly notice might totally fog a film, as film is more sensitive to blue light than our eyes are.

    Ian
     
  6. gma

    gma Member

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    Thanks for the explantions. I knew that panchromatic film can be examined briefly under a weak green safelight during development at some distance, but I am surprised that the seemingly bright green LED very near the film did no damage. The J&C Classic films have greater sensitivity to red than most pan films. Maybe green sensitivity is less than most?
     
  7. Gerald Koch

    Gerald Koch Member

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    Not only is the human eye most sensitive to green light but most films have their lowest spectral sensitivity in the green region. A fortuitous combination.

    The human eye is far more sensitive to light than even the fastest film. I have loaded film onto reels in what I thought was total darkness only to find that I was beginning to see the reels near the end of my task. These negatives showed no sign of fogging. Not something I recommend but no harm in this case.
     
  8. steve

    steve Member

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    When I was a freshman at Rochester Institute of Technology, we were taken on a tour of Kodak to see both film and paper being made. The took us into one of the film coating facilities and into the coating area itself. The work area was illuminated with extremely dim green safelights. As stated in several previous posts, the eye is most sensitive to green which is exactly why green was chosen as the safelight color in the coating facility.
     
  9. Ole

    Ole Moderator Staff Member Moderator

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    It's amazing how much light you can have in a darkroom without fogging film!

    Eyes adapt to low light, film does not.
     
  10. photobackpacker

    photobackpacker Advertiser Advertiser

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    The film need not show signs of fogging to be changed by low-level light exposure. Even if the exposure does not break the threshold level needed to cause fogging, it will likely be more sensitive to exposure and may well be a bit flatter in contrast.