Blue light bulbs abd availability of lightbulbs

Discussion in 'Enlarging' started by LF2007, Apr 12, 2009.

  1. LF2007

    LF2007 Member

    Messages:
    17
    Joined:
    Jan 6, 2007
    Shooter:
    35mm
    I just received a second hand enlarger off e-Bay. It came with a blue 75 watt Philips- lightbulb (transparent). Why would anyone use a blue lightbulb? Does it have any advantages in printing?
     
  2. Cruzingoose

    Cruzingoose Member

    Messages:
    211
    Joined:
    May 27, 2006
    Location:
    South Dakota
    Shooter:
    Medium Format
    Blue bulbs

    Most likely it was handy and it fit. There is no real reason to use a blue or daylight bulb in a conventional enlarger. I DO use two blue 7 watt and a 7 watt orange "golf bulbs" in my Brumberger 7x5 contact printer. They do a much better job in managing contrast and allows 10-15 second exposures using VC paper.
     
  3. ic-racer

    ic-racer Member

    Messages:
    7,470
    Joined:
    Feb 25, 2007
    Location:
    Midwest USA
    Shooter:
    Multi Format
    A blue filter blocks the light the paper does not see.

    What kind of enlarger is it? Perhaps someone can give a good suggestion on a bulb for that enlarger. Some enlargers have specific requirements.
     
  4. LF2007

    LF2007 Member

    Messages:
    17
    Joined:
    Jan 6, 2007
    Shooter:
    35mm
    It's a Leitz Valloy II

    Can I also use regular lightbulbs available in supermarkets?? Or does it have to be a special type of bulb?

    I learned that in Europe regular lightbulbs will be banned by 2012. All lightbulbs will be replaced by energy saving lightbulbs. Not sure if you can use energy saving lightbulbs in an enlarger, as they need warm up time. Anyone have experience with them?
     
  5. alistair56

    alistair56 Member

    Messages:
    4
    Joined:
    Jan 28, 2009
    Shooter:
    Medium Format
    I have a magnifying glass on an extendable arm that came with a tungsten blue bulb. I bought it from someone who did embroidery. According to the manual the blue bulb was to correct the colours of the embroidery thread - a bit like a tungsten filter I guess
     
  6. ic-racer

    ic-racer Member

    Messages:
    7,470
    Joined:
    Feb 25, 2007
    Location:
    Midwest USA
    Shooter:
    Multi Format
    Ok, so you have a great enlarger. Certainly worth fixing up right. You may be able to get by with a regular 75W bulb, but for best even illumination I'd look for the correct bulb.
    Glennveiw has a correct Osram 75W bulb for $15, but I think its the same as the PH/211, here for $5:
    https://www.lightbulbemporium.com/eiko_03663ek_ph_211.asp

    This picture from glennview.com shows the box for the Osram bulb.
    [​IMG]

    I don't live in Europe, but I don't think those regulations apply to specialty lamps.
     
    Last edited by a moderator: Apr 13, 2009
  7. srs5694

    srs5694 Member

    Messages:
    2,725
    Joined:
    May 18, 2005
    Location:
    Woonsocket,
    Shooter:
    35mm
    Just speculation, but: A blue bulb, depending on its exact characteristics, might produce a higher-contrast print on variable contrast (VC) paper than would a white bulb. It's conceivable that the enlarger's original owner liked this and so used a blue bulb to get this effect. Of course, I have no way of knowing this is so; you'd have to run some tests to even verify that the bulb has this effect. If you know who the original owner was, you could ask.
     
  8. ic-racer

    ic-racer Member

    Messages:
    7,470
    Joined:
    Feb 25, 2007
    Location:
    Midwest USA
    Shooter:
    Multi Format
    Blue or cyan filters have no effect on VC or non-VC paper. They block light outside of the paper's sensitivity spectrum. The paper doesn't know or care :wink:
     
  9. Steve Smith

    Steve Smith Subscriber

    Messages:
    9,079
    Joined:
    May 3, 2006
    Location:
    Ryde, Isle o
    Shooter:
    Medium Format
    Some grain focusers come with blue filters to allow better focussing as you are only seeing the light the paper sees. A blue bulb could have the same effect but this may not be the reason it was fitted.


    Steve.
     
  10. Adrian Twiss

    Adrian Twiss Member

    Messages:
    623
    Joined:
    Jan 19, 2004
    Location:
    Wigan (oop N
    Shooter:
    Multi Format
    The problem with regular bulbs is that they have the branding and wattage information on the top of the bulb. There is a danger it would be projected onto the print. Enlarger bulbs (apart from their very even coating) have the branding and wattage printed on the side.
     
  11. srs5694

    srs5694 Member

    Messages:
    2,725
    Joined:
    May 18, 2005
    Location:
    Woonsocket,
    Shooter:
    35mm
    Cyan, yes (in theory; in practice a cyan bulb, especially one made for non-photographic purposes, might not be pure cyan and so might have some effect). Blue, no. VC papers are sensitive to blue and green light, so if you use a blue filter (which blocks green and red light), you end up changing the contrast, since you'll be reducing the amount of green light that hits the paper.

    The OP identified the bulb as blue. If that's accurate, I'd expect it would have some effect. Of course, people often misidentify cyan as blue; or the color might be light enough or impure enough or affect only certain frequencies and so have little or no real effect. Testing is the only way to be sure.
     
  12. srs5694

    srs5694 Member

    Messages:
    2,725
    Joined:
    May 18, 2005
    Location:
    Woonsocket,
    Shooter:
    35mm
    Patrick Gainer did some tests that were published in Photo Techniques a while back. I believe the article was titled "Hazards of the Grain Focuser" or something similar. He found that using blue light is not the best choice for focusing; using either green light or white light works best. Using blue or red light results in misfocusing. This isn't about what the paper sees; it's about what our eyes see; the lenses in the human eye are really pretty bad in many respects, and in particular they focus different wavelengths differently, resulting in focus errors when you focus using light of certain colors.
     
  13. ic-racer

    ic-racer Member

    Messages:
    7,470
    Joined:
    Feb 25, 2007
    Location:
    Midwest USA
    Shooter:
    Multi Format
    Yes, good point, I was mistaken. A proper blue will add some contrast to each filter grade in a filter set. Its just the non-MG papers that won't care.