compact flourescent bulbs in enlargers

Discussion in 'Darkroom Developing and Printing' started by Robert Feinman, Dec 3, 2003.

  1. Now that there are a wide variety of screw base flourescent
    bulbs offered, I'm wondering if they might be useful instead
    of a 212 or like enlarger bulb.
    It would seem that the high blue and green content would make
    the exposure times short and there would be little heat.
    I suppose it would be necessary to leave the bulb on and use
    some sort of shutter to control exposure.
    Anyone ever try this?
     
    Robert Feinman, Dec 3, 2003
    #1
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  2. It should work fine in a diffusion enlarger. A condenser
    enlarger (the ones with a 212 bulb) sort-of images the bulb
    on to the back of the lens. As such, a s-b fluorescent made from
    bent up tubing may not provide even illumination.
    Color balance may be an issue with VC paper. The early/
    standard Aristo cold-light heads did not work well with
    VC: lots of blue light, not much green; prints made with
    these heads were _very_ contrasty.
    Yup. Aristo heads utilize a heater to keep the lamp warm.
    It should only take 5 minutes. Less time than
    it takes to talk about it.
     
    Nicholas O. Lindan, Dec 3, 2003
    #2
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  3. I imagine you would hate them.

    1.) They are much dimmer than incandescent bulbs of the same claimed
    luminousity.

    2.) They take a minute or so to come up to full brightness, so you will
    never know what exposure time to use unless you leave the lamp burning
    all the time and figure out another way to make the exposures. And while
    the lamp is burning, the light that always leaks from the enlarger will
    be fogging any paper it falls on, directly or indirectly.

    3.) They tend to be much larger than an incandescent bulb, and probably
    will not fit existing enlargers.

    4.) You will have to calibrate your printing filters all over again if
    you intend to use VC paper because their spectrum tends to be a line
    spectrum, though smoothed over a bit by the phosphor coating inside. But
    if you examine the spectrum with a diffraction grating you can plainly
    see the lines.

    5.) Their luminance vs. input voltage varies much more than a comparable
    incandescent bulb.

    6.) Unless you are using a diffusion enlarger with a very efficient
    diffuser, the nonuniformity (the hairpin tubes, or the helix tube) will
    make even exposures very difficult.
     
    Jean-David Beyer, Dec 3, 2003
    #3
  4. Robert Feinman

    Jorge Omar Guest

    I've tried this idea.
    First, a 20W white light one. Too short exposure times due to lots of
    blue output.
    Then a 9W one. Good exposure times, but then I felt the light was too dim
    for confortable focusing.
    I gave up.

    Jorge
     
    Jorge Omar, Dec 3, 2003
    #4
  5. Its worth a try but most of these lamps are lower in
    intensity than a 212, which is 150watts. I think it might be
    closer to a PH211 (75 Watt) lamp. The 211 is the one most
    often used in enlargers like the Omega D-2. Condenser
    enlargers image the surface of the lamp on the lens. You
    might need an auxillary diffuser over the bottom of the lamp
    to get uniform illumination. Probably a disc of thin
    diffusing plastic would do. Again, it should not be
    difficult or expensive to try this out.
    I have given these lamps some thought as a possible source
    in a diffusion source for converting an 8x10 camera into an
    enlarger. The lamps are self contained and need no starter
    or ballast so all one needs is sockets. Since my concept is
    one where a lens in a shutter will be used the lamps can be
    kept burning throughout a session. Fluorescent lamps like to
    run hot. The compact lamps are no exception and take several
    minutes to come up to full intensity.
    Another place these lamps may be useful is where the
    original enlarger lamp is no longer available as is the case
    for large Elwood enlargers. These use a combination of an
    eliptical reflector and diffusion glass so the exact shape
    of the lamp may not be critical. The original lamps were 300
    to 500 watts so it might be difficult to get enough light
    from a compact fluorescent.
    The compact lamps I use as houshold lamps have a visual
    color similar to incandescent lamps. I suppose you could get
    the actual spectral curves from General Electric or other
    manufacturer of the lamp. If the spectrum is not too
    different it would make the use of variable contrast filters
    possible.
     
    Richard Knoppow, Dec 3, 2003
    #5
  6. The also make fluorescents with the inside of the tube coated in
    /green/blue/(uv?) radiating powders for a 'whiter' light and for grow
    lamps... Artist's lamps are also doped to give a color temperature closer
    to sunlight... Don't know if the coiled compacts, are included in that, but
    I will do a bit of a google and see if I find any...
    My reading light at my bed side is a coiled compact... I noticed last night
    <because I was thinking about this> that it is actually more yellowish than
    the usual fluorescent greenish... Interesting...
    Denny
     
    Dennis O'Connor, Dec 4, 2003
    #6
  7. Dennis O'Connor, Dec 4, 2003
    #7
  8. Robert Feinman

    dr bob Guest

    I have made some experiments with these in my old DII and can
    definitely confirm Jean-David's conclusions, especially about the light
    unevenness. It was BAD - not worth the effort.

    Truly, dr bob.
     
    dr bob, Dec 4, 2003
    #8
  9. Robert Feinman

    G.P Guest

    They are made to from warm to cool temperatures, although most are warm
    (2700 & 3000K).

    Guillermo
     
    G.P, Dec 4, 2003
    #9
  10. They have a lamp for reptiles that is in 5700K range... Well above warm...
    You will need a UV filter with VC paper...
     
    Dennis O'Connor, Dec 4, 2003
    #10
  11. Robert Feinman

    Dan Quinn Guest

    RE: Robert Feinman <

    A 4x5 enlarger I picked up surplus in 1959 used, IIRC, five,
    short, small diameter tubes. It worked well.
    What size of enlarger do you have in mind? Ultra thin light
    boxes use 1/10 inch diameter tubes. Dan
     
    Dan Quinn, Dec 4, 2003
    #11
  12. Strictly speaking, fluorescent lamps _do not have a color temperature_
    since they produce a line spectrum, not a continuous one. True, the
    phosphors put in a few more lines between the ones produced by the gas
    in the tube, but you can still see the lines very clearly when you
    observe the light with a diffraction grating. I imagine a prism would
    reveal the lines as well.
     
    Jean-David Beyer, Dec 5, 2003
    #12
  13. Well, the Beseler 4x5 uses a 211 or 212 bulb which is the same size
    as a household 100 watt bulb.
    I have a couple of household flourescents which are in regular sockets
    and the bulb envelope is "bulb" shaped and not a spiral or zigzag.
    Flourescents put out a strong green and blue line because of the
    mercury in the gas. This is modified by coating inside the bulb which
    absorbs the UV lines and converts them to visible light.
    Since b&w paper is blue and/or green sensitive the lamps may be
    more efficient than the nominal wattage would indicate.

    This might also solve the problem of the person with the old Solar
    enlarger. Not as bright as 300 watt original, but brighter than
    nothing!
     
    Robert Feinman, Dec 5, 2003
    #13
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