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  1. #1

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    How to reduce output from cold light enlarger?

    I recently ran out of graded fiber base paper and ended up reaching for a box of graded RC. I am actually quite pleased with the prints and will continue to use the paper. The enlarger is an Omega 4x5 with the Omega cold light.

    Here's the rub: The paper is way too fast for my setup. If I print at my sharpest f/stop then my times are uncontrollably short. To get times I can live with I must stop all the way down. I can literally watch the grain blur as I stop down, so I know I am giving up sharpness/acutance.

    Has anyone come up against this? Are there neutral density filters for the Omega? I would prefer not to peck around with electrical mods because I do not want to zap myself and I do not wish to possibly spoil a lovely setup.

    Any help is welcome.


    jon

  2. #2

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    I would consider adding neutral density into the light path above the negative by adding equal amounts of color printing filters(C,M,Y), if you have them. If you don't then I would look to material like Rosco Lux which comes in neutral shades of gray of varying densities.

  3. #3
    jnanian's Avatar
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    aristo also sells a dimmer that can reduce your output.

  4. #4
    Ed Sukach's Avatar
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    Quote Originally Posted by jon koss
    The enlarger is an Omega 4x5 with the Omega cold light.

    Here's the rub: The paper is way too fast for my setup. If I print at my sharpest f/stop then my times are uncontrollably short. To get times I can live with I must stop all the way down. I can literally watch the grain blur as I stop down, so I know I am giving up sharpness/acutance.
    Has anyone come up against this? Are there neutral density filters for the Omega?
    What lens/es are you using? I have two Rodagons on my Omega and they are both front threaded for 40.5 mm filters. Certainly, the usual Neutral Density filters may be used ... from 2x to 10x.
    Carpe erratum!!

    Ed Sukach, FFP.

  5. #5
    gainer's Avatar
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    I don't know much about cold light enlargers, but would expect them to have a filter drawer far enough above the neg carrier to be out of focus on the base board. If that is the case, you might try using a piece of black window screen in the filter drawer.
    Gadget Gainer

  6. #6
    David A. Goldfarb's Avatar
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    Cold light heads usually don't have a filter drawer, because they need to be close to the neg for even light distribution, but it's possible to put gel filters between the head and the neg, and I've seen an arrangement where someone made a filter drawer that only added 1 inch between the head and the neg with no ill effects. I'd go with the suggestion of adding an ND lighting gel between the head and the neg or an ND filter to the lens with a step-up ring if you don't happen to have the right filter diameter. I suppose you could even add a yellow filter, which you probably have on hand, below the lens, since there is no variable contrast issue and graded papers are mostly blue sensitive.

  7. #7
    sparx's Avatar
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    Quote Originally Posted by jon koss
    To get times I can live with I must stop all the way down. I can literally watch the grain blur as I stop down, so I know I am giving up sharpness/acutance.
    Perhaps i'm being thick here but i was always led to believe that smaller aperture = sharper image, both in picture taking and printing. Is this not the case?
    [size=1]the all new darkplanet photoblog[/size][size=1]
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  8. #8
    David A. Goldfarb's Avatar
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    A smaller aperture increases DOF and reduces certain aberrations, but increases diffraction, so the optimum aperture is not typically the smallest one.

  9. #9

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    I don't know about your head exactly, but my older D2 with an Aristo cold light uses a white plexiglass diffuser to even out the illumination. If you have something similar, you could take that peice to a plastics retailer and they could cut an extra one to put on top or a thicker one that should reduce light output.
    "Fundamentally I think we need to rediscover a non-ironic world"
    Robert Adams

  10. #10
    juan's Avatar
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    I had a glass place cut a round piece of ground glass (they probably called it dusted or some such thing) the diameter of the cold light. I dropped it into the enlarger where the cold light fits in, then added the cold light on top. It added even more diffusion and cut the light by a couple of stops or so.
    juan

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