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  1. #1
    swittmann's Avatar
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    (WTB) ND filter for enlarger

    Hi all,

    I am looking for a ND filter for my enlarger. I have an Opemus 5a. The filter drawer holds filters of 7x7 cm (2.75x2.75 inch).

    The reason is that I have a new RHD Analyser Pro and want to calibrate it to my papers. For this, I need to reduce the light to get times that I can work with.
    (For those of you who are familiar with the Analyser, the first reading gives me a time of 3.41 seconds, but I need to achieve a time between 10 and 20 seconds, so a filter of about 1.5 stops should do fine if I am not mistaken. Yes, the lens is stopped down to minimum aperture and the enlarger head is in its highest position.).

    Any help/offer would be greatly appreciated.

  2. #2
    L Gebhardt's Avatar
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    Do you have a polariser or ND filter you can screw into the lens. That would be the easiest option, and the one I use when i need to reduce the light level.

  3. #3
    swittmann's Avatar
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    I have a ND filter, 77mm, for a camera lens. Well, I use Ilford under-the-lens contrast filters, so at the moment, I have no idea how to use both at the same time (except maybe hand-holding the 77mm filter, which sounds a bit awkward...).

    A step-down ring would not help much in this setup, would it?

  4. #4
    MattKing's Avatar
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    Do you know anyone who shoots 5x4, and could expose and develop an out of focus, thin negative for you?
    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
    swittmann's Avatar
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    Matt and L Gebhardt, thank you for your help.

    Matt, unfortunately not...

    I found a shop that sells screw-in filters with a small enough diameter to fit my enlarger lens (just 30mm; a Meopta Anaret 4.5/80mm). L Gebhardt, this is this the kind of filter you were thinking of, isn't it? (link)

  6. #6
    MattKing's Avatar
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    If I recall correctly, the Opemus enlargers use a tungsten bulb as a light source. If so, you could use a dimmer to lower the light output.

    You need to be careful with a few things though - dimmers change the colour temperature of the light emitted, and variable dimmers may make it hard to get repeatable results.

    Here is a "how to" video link:

    http://www.dailymotion.com/video/xce...tch_shortfilms
    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

  7. #7
    MattKing's Avatar
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    Sandra:

    The material referred to in this thread would also work:

    http://www.apug.org/forums/forum41/9...ml#post1199634
    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

  8. #8
    swittmann's Avatar
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    Matt, thank you once again. My Opemus 5a is a condensor enlarger with an opal lamp. I found an overview here: http://www.meoptahistory.com/?id=312 (please scroll down, it is almost at the bottom of the page).

    I just opened the lamp house of my enlarger to see how many watts my bulb has: 150 W. Maybe the easiest way of all would be to buy a new bulb with 75 W because mine is very old (I never changed it, shame on me, and the previous owner... I have no idea if and/or when he changed the bulb). Fotoimpex has them for just around 10 Euros. However, would a 75 W increase the time by 50 %? Then I would end up with around 6,82 seconds, which is still not long enough, and then I could try your suggestion or get one of these ND filters.

  9. #9
    Mainecoonmaniac's Avatar
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    Don't know if these will work, but they're 20"x24". You can cut them to size.

    http://www.amazon.com/Rosco-Cinegel-...8869747&sr=8-4

  10. #10
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    Quote Originally Posted by swittmann View Post
    Matt, thank you once again. My Opemus 5a is a condensor enlarger with an opal lamp. I found an overview here: http://www.meoptahistory.com/?id=312 (please scroll down, it is almost at the bottom of the page).

    I just opened the lamp house of my enlarger to see how many watts my bulb has: 150 W. Maybe the easiest way of all would be to buy a new bulb with 75 W because mine is very old (I never changed it, shame on me, and the previous owner... I have no idea if and/or when he changed the bulb). Fotoimpex has them for just around 10 Euros. However, would a 75 W increase the time by 50 %? Then I would end up with around 6,82 seconds, which is still not long enough, and then I could try your suggestion or get one of these ND filters.
    Try it but be careful. As for dimming bulbs, lower-wattage bulbs often (but this is absolutely not a rule) run at lower temperature and therefore have redder light, which will give you less contrast.

    If you use a lower-wattage bulb, make sure it's a halogen and get the whitest-looking one you can find. Getting some ND gel seems like an easier approach.

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