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  1. #1
    SMBooth's Avatar
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    Durst 1000 - Blue filter

    Ive put together a darkroom, my 'new' enlarger is a Durst 1000 with condensers and bulb which requires a filter set for contrast. I'm curious to know why previous user inserted a blue filter between the lamp and condenser. Should I remove it to get correct contrast filtering or does the blue filter improve something I don't know about.

  2. #2
    Chris Lange's Avatar
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    it's supposedly better to focus with blue light because that is the color that photographic papers are traditionally sensitized to see. focusing with white light, in theory, is less accurate because the different wavelengths of light focus at different distances.

    that said, in practice, I have never seen a difference.
    See my work at my website CHRISTOPHER LANGE PHOTOGRAPHY

    or my snaps at my blog MINIMUM DENSITY
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  3. #3
    SMBooth's Avatar
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    I did read after posting that a blue filter will reduce contrast when using a condenser enlarger setup, but that was Popular Mechanics.....
    I guess I'll do some step wedge tests tonight.

  4. #4
    MattKing's Avatar
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    A blue filter would increase contrast with variable contrast paper. Is the light source quite green or yellow without it?
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  5. #5
    SMBooth's Avatar
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    No its a typical white photo 150 watt photo lamp for enlargers. Printing tonight with it seemed OK. I have not put the step wedge under it yet.

  6. #6

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    I can't think of a good reason to leave the blue filter in. The blue/focus thing is baloney. As for contrast, it would theoretically give you maximum contrast with VC paper (although it depends on the specific spectral sensitivity of the paper and spectral transmission of the particular blue filter. Printing speed will be reduced to varying degrees. With graded paper the only effect would be reduced printing speed.

  7. #7
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    I have a blue filter accessory for my Grain focuser, and folks have often commented how sharp my prints are... Of course I have never ever used the thing (and why would I? It just makes everything annoyingly darker!).

    Marc!
    Marc Morel
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  8. #8
    ath
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    It might be in fact a heat and/or UV absorbing filter.
    http://www.tmax100.com/photo/pdf/L1000.pdf section 3.1.1
    Last edited by ath; 08-28-2012 at 07:57 AM. Click to view previous post history.
    Regards,
    Andreas

  9. #9

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    Neither a heat absorbing filter nor or a UV absorbing filter would have a visible blue color. (A UV filter wouldn't be blue anyway). Putting a visible-spectrum blue filter in the light path can only interfere with VC contrast control as a blue filter will attenuate green light.

  10. #10
    ath
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    The heat absorbing filters I know have a greenish-blueish cast. Maybe the OP could comment if the filter has a colour cast or a strong distinctive colour?
    Regards,
    Andreas

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