Household fluorescent lamps

Discussion in 'Darkroom Equipment' started by Fred Aspen, Jul 2, 2008.

  1. Fred Aspen

    Fred Aspen Member

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    Perhaps an inane question, but I have a Durst M300 that uses the common 60W household lamp as a light source. The thought occurred to me that I could replace it with the new fluorescent lamps sold at the big box stores.

    Would I now have an M300 with a cold light head? I am sure it would help negative popping. Anyone try this?

    Fred
     
  2. Monophoto

    Monophoto Member

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    Fred -

    Probably not a great idea.

    One of the technical concerns with compact fluorescent lamps is their "warm-up" characteristic - it takes several minutes for them to achieve full light output. Visually, they are noticeably dimmer when you first turn them on but appear to achieve full brightness after about 30-45 seconds. Technically, however, it takes around four minutes for them to actually achieve full light output.

    That would make them quite impractical for enlarging applications where the usual 'on-time' is 10-30 seconds. Also, because the warm-up characteristic is caused by the fact that a mercury amalgam has to vaporize before the lights achieve full output, and turning off the power prematurely allows the amalgam to redeposit abnormally, operating CFLs for periods of time significantly shorter than the warm-up time actually reduces their life expectancy.

    The best way to avoid negative popping is to preheat the negative before making the exposure. Turn on the enlarger for a few seconds before doing the final focus. Then turn it off, load in the paper, and then turn it back on while holding a card below the lens to keep light from falling on the paper. After a few seconds, remove the card to start the printing exposure.
     
  3. Fred Aspen

    Fred Aspen Member

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    Thanks, Louie, I figured there were problems with the idea but, with the temperatures outside right around 100, the mind works overtime when it isn't photographing.

    -Fred
     
  4. Fred Aspen

    Fred Aspen Member

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    Well, in spite of the aforementioned warnings, and the fact it is 100 outside, I installed the household flourescent lamp in place of the incandescent bulb into the Durst M300 and created a condenser enlarger with a 'cold light' head. I proceeded to make a few prints.

    I preheated the lamp but today's flourescent bulbs are pretty bright right away. I didn't see any perceptible difference between a preheat and no preheat.

    What did occur, however, was that I had some pretty thin, flat negs that I shot in the shade and the fluorescent lamp really put the sparkle (contrast) into those prints. The color temperature of the lamp was equivalent to turning a grade 1 neg (with no contrast filter) into a grade 4 print. Most likely because the lamp is predominately blue-green rather than orange-red of the incandescent. Printing time was about double what was required with the incandescent, about 7 sec. I am using Ilford MG IV.

    Not that this has any particular meaning but I thought I would pass the results along. I also did not get any negative pop.

    The change, however, would definitely be helpful in turning normal negs into 'Ralph Gibson' style prints without all the hassle of trying to remember where the #5 contrast filter went or smoking the negs in some hot developer!

    Sorry, I don't have any of those digital contraptions to post the before and after results.

    My .02,

    -Fred
     
  5. JBrunner

    JBrunner Moderator Staff Member Moderator

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    Ole has reported using one of these as working well.

    I tried one in one of my diffusion enlargers, and it was a disaster:

    http://www.apug.org/forums/forum43/45629-non-scientific-cfl-enlarger-experiment.html

    Other have met with different results as well, some good, some bad. There is some really good info in the thread.

    Seems to depend on the enlarger type, how it illuminates, etc. The bulb I was using wasn't reliable as far as heat performance went. The color temperature issue, are however what made me abandon the project in regard to my diffusion enlargers. I suspect the output of a condenser enlarger would mitigate the uneven CT illumination problem.
     
  6. domaz

    domaz Member

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    How about a 60-watt equivalent LED light bulb instead?

    Not cheap though. There are "accent" LED bulbs that are far cheaper but they probably won't put out quite enough light to be useful.