Green LED Lights in Darkroom

Discussion in 'Film and Processing' started by Henricvs, Nov 10, 2019.

  1. I am preparing my long awaited darkroom. When we moved to a new home I had a 15'x16' room built with plumbing for a sink. The room is accessed from my utility room so I have a baffle of sorts from the outside light. The room is nice and dark with no need for door or window blocking. As the room is a good size and out of the way, I put my TV/Internet modem in there too. You guessed it, green LED lights. Covering these would not be difficult, but should I? Will such small green lights cause problems with printing?
  2. Probably not. Dim green filters were used on safelights for processing black and white film by inspection, but not because the film wasn't sensitive to green. Green was used because the eye is supposedly more sensitive to it. I've even heard of using a candle on the other side of the room as a safelight. Do a fogging test where you partially expose paper, then add the fogging exposure to part of it, usually about 5 minutes. My guess is you'll have no trouble.
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  3. Photographic print papers come in many flavor however only three, fixed contrast grade and variable contrast black & white and color printing are in common usage. The fixed contrast black & white papers are only sensitive to violet and blue. They should be OK if exposed to green light. One truly never knows because the frequencies outputted by the green LED's could include some blue hues. Variable contrast black & white papers have two light sensitive emulsions. One is blue sensitive and the other is green sensitive. We print with these papers by using various shades of magenta (green blocking filters) and yellow (blue blocking filters. In other words, these papers could easily be fogged if exposed to green. Color papers have a green sensitive emulsion. Again, we don't know if the green LED;s will fog but we expect so. Easy to to test. Lay out a sheet of photo paper face up in the work area. Scatter 10 or so coins atop. Each 2 minutes, remove a coin. Now develop the paper. If the green LED have an effect you will see fogged paper. The areas under the coins were exposed over various times. This developed paper will tell you how long the paper can allow the paper to linger in the work area.
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  4. As Alan says.

    If you don't test, for sure, cover the LEDs. Green safe lights were sometimes used for panchromatic films, but in really, really dim intensities.

    When I started developing, the 620 films I used were orthochromatic; and I used to develop by inspection in trays with a red safelight. It was neat to see the image emerge on the film.

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  5. LED's are fairly monochromatic in character, so a green LED shouldn't affect graded bromide paper. Multicontrast paper, OTOH, is designed to be green sensitive, as obviously is colour paper.

    I suspect that LEDs will have little effect in the darkroom unless they shine directly on the paper. However, personally, I'd tape over the LEDs just to be on the safe side. I did that with any equipment having an indicator LED or neon in my own darkroom. In fact what I did was fit a little flap of black paper over the indicators so that the paper could be lifted to verify the state of the lamps.

    P.S. interesting to see that Ansco were a division of GAF. I always thought that they were associated with Agfa, but then Ansco never had a very high profile in the UK - about on a level with Ferrania or Perutz.
    Last edited: Nov 11, 2019
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  6. LEDs can be pretty bright.

    I little black tape should reduce most of it.

    As above, variable contrast papers are green sensitive.
    Light not bright enough to actually expose paper can affect other exposure,
    so should be minimized.

    I believe that yellow LEDs are most often far enough not to cause problems, and
    maybe even can work with color paper.

    Note that unlike film, it is not necessary for color paper to be sensitive to all
    wavelengths. Each color layer needs to be appropriately sensitive to the light
    from its layer in the negative. The sensitivities of color paper are arranged to
    have a narrow range with low sensitivity that can be used with a fairly dark
    (#13) safelight. There might be yellow LEDs also near that wavelength that
    can be used as safelights.

    Reminds me, of the rare times that I have film out in my darkroom
    (that is, not in a changing bag) wondering who invented glow in the dark timers.
    Henricvs likes this.
  7. Darkroom at uni had a very good digital enlarger timer.

    With a BRIGHT RED led readout, bright enough to cast shadows.

    Never seemed to cause any issues though. I stuck a piece of masking (paper) tape over it, could still read the display, but the glow was greatly reduced. Obviously, it was off when working with film!
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  8. They were a part of Agfa - until World War II. At the start of the war German and German company assets were seized by the government. You can read about it here:

    Ansco - Wikipedia
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  9. Why take chances. Cover the modem lights with removable tape. Takes less time than running tests and is less expensive; it does not require the sacrifice of any photographic paper.
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  10. You're right, just curious, I do plan on tossing a towel over it while I work.
  11. I know some folks may get annoyed at questions like this, but I love the responses. There is so much to learn from the experienced here.
  12. When I first started darkroom work, my dad bought some supplies from a Goodwill store, including a contact printer and red Brownie safelight.

    By then, panchromatic films had been around long enough that the Brownie came with yellow and green filters.

    I did use the red one for printing when it was the only one I had.

    Not so much later, I inherited some darkroom equipment from my grandfather, including
    a Varigam safelight. (Close enough to Polycontrast.) Also a set of Varigam contrast filters.
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  13. Varigrade / Polycontrast paper is still insensitive to red light, and a 'normal' red/orange safelight can be used. Red and amber LEDs will also do no harm, but green and blue LEDs are a definite no-no unless they're very dim or obscured.

    FWIW, I discovered that some white melamine surfaces, such as are often found on kitchen units, can be fluorescent and have a noticeable decay time after being exposed to bright light. Not much of a practical issue, but it can be disconcerting to see a faint green glow from your work surfaces after you switch off the white light in your darkroom!
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  14. As above, I have a darkroom timer with a glow in the dark front. I put it in a black bag when doing film work.

    Kodak warns against the afterglow of fluorescent lamps, which might not be unusual in darkrooms.
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  15. Film has not been "developed by inspection" since the 1940's (and with dramatic license in movies and on TV). At the newpaper where I worked, there were pocket doors with sweeps to prevent even that little bit of light leakage. Once loaded into "daylight" tanks, the lights could come on. The only timers with phosphorescent dials were in the print room.

    B&W paper, on the other hand, is mostly orthochromatic, sensitive only to blue light. We used mostly variable contrast paper, working under yellow-green "OA" filters. Even so, developing by inspection is not something professionals do. If you want good blacks and gradation, you use a timer. The light is just to see your way around, and while agitating the paper during processing. The print room didn't even have doors. The entrances were labyrinths.
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  16. Orthochromatic films are still around, and even more new ones just came from Ilford.

    But now, "develop by inspection" usually means with the dark green #3 safelight.

    I have had a Brownie with the green filter for many years, which I never used.

    My darkroom now, built by the previous house owner, has an 8x10 #3 safelight,
    which I have never used.

    The theory is that by half way though development that enough sensitizing dye
    has been removed, such that some green light can be used, which is near the
    peak dark human sensitivity. However, with the undeveloped silver halide still
    there, you can't see through the film. Or maybe just enough?

    Over the years, I used Diafine most, which doesn't really allow for development
    by inspection. It could be interesting to try, just to see what happens, though.
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  17. In photography, particularly the darkroom, it is better to be consistent than subjectively correct. Time and temperature are your friends, and the salvation of dilettantes.
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