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  1. #1

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    Can I HID Lamp as cold light source !?

    Hi all,
    I want to DIY my cold light source for my LPL7452.

    I found the HID lamp(the lamp for car ) have colour temp from 6500K to 12000K...
    Also, the stabilizer output fit with the HID power control gear...

    So, do anyone know, if I want to do this, which colour temp. good for this ?


    THX

  2. #2
    ic-racer's Avatar
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    Hmmm... lets see, characteristics of HID are, unstable color temp, unstable operating voltage through life cycle, heat generation, slow ignition, need for a ballast. I think they are good for illuminating baseball fields.
    The ionization voltage of all HID lamps increases greatly when the lamp is hot. If power to the lamp is interrupted, the lamp must be allowed to cool for a time, usually several minutes, before the arc can be reestablished and normal operation resumed
    ---http://www.unvlt.com/techsupport/trouble_shooting/HID_tech_guide.html
    I would rate HID lamps as probably the least suitable for photographic enlarging.

  3. #3
    onepuff's Avatar
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    HID lamps are not suitable for enlarging as they are not "full spectrum" lamps. They emit light at a number of wavelengths which when combined give light at a given colour temperature but have significant gaps in their spectrum so will not render correct exposure results when using photographic paper.
    " ... a cook who relies on nothing but a sharp knife has no guarantee of producing excellent dishes." - Yoshihisa Maitani

  4. #4

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    OOO ic...
    I will give up the HID ...
    thx onepuff

    by the way, do the Fluorescent lamps produce full spectrum and suitable for BW paper ?

  5. #5
    Christopher Walrath's Avatar
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    However, they do well as $200 headlights. Really.
    Thank you.
    CWalrath
    APUG BLIND PRINT EXCHANGE
    DE Darkroom

    "Wubba, wubba, wubba. Bing, bang, bong. Yuck, yuck, yuck and a fiddle-dee-dee." - The Yeti

  6. #6
    RalphLambrecht's Avatar
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    I never understood why cold light sources were so popular with some people anyway. They have few benefits and many disadvantages as far as I can tell. I find regular color heads or contrast filtration to be far superior.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  7. #7
    Curt's Avatar
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    I agree; I was in the Aristo Cold Light head circle, owning several, but with major improvements in variable contrast paper several decades ago and the move to a color head had me asking why I needed a cold light head, tube type, at all. With built in dichroic filters and no limit to the intermediate settings, I see no need to go back to the cold light head. There have been a few things that have changed in photography as far as equipment availability and I've had to stop and evaluate each one for it's practical use. Two events happened; one is the availability of cheap color heads due to disuse in the industry and the demise of Aristo as a supplier. So I see color heads as a great diffusion light source with great adjustment controls.
    Everytime I find a film or paper that I like, they discontinue it. - Paul Strand - Aperture monograph on Strand

  8. #8

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    Curt,you don't happen to have any 5x7 cold lights hanging around that you want to get rid of,I can of need one.
    Mike

  9. #9
    ic-racer's Avatar
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    Quote Originally Posted by RalphLambrecht View Post
    I never understood why cold light sources were so popular with some people anyway. They have few benefits and many disadvantages as far as I can tell. I find regular color heads or contrast filtration to be far superior.
    I have wondered about it also. My thought is that 'way back when' the coldlight had some advantages over the NON-Dichoric heads.

    With the advent of Dichoric heads, the coldlight does not compare so favorably. When you think about it dichroic filters are a pretty amazing concept. Heat and fade proof. Some people don't realize what a near-perfect light source they can make.

  10. #10
    Steve Smith's Avatar
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    Quote Originally Posted by ic-racer View Post
    When you think about it dichroic filters are a pretty amazing concept. Heat and fade proof.
    It doesn't stop some people asking where they can get replacement filters from as theirs have 'faded' though!


    Steve.

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