(WTB) ND filter for enlarger

Discussion in '[Classifieds] Want to Buy' started by swittmann, Jun 22, 2011.

  1. swittmann

    swittmann Member

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    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. L Gebhardt

    L Gebhardt Subscriber

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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. swittmann

    swittmann Member

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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...). :sad:

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

    MattKing Subscriber

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    Do you know anyone who shoots 5x4, and could expose and develop an out of focus, thin negative for you?
     
  5. swittmann

    swittmann Member

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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. MattKing

    MattKing Subscriber

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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/xcei63_the-frugal-filmmaker-dimmer-switch_shortfilms
     
  7. MattKing

    MattKing Subscriber

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  8. swittmann

    swittmann Member

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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. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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  10. polyglot

    polyglot Member

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    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.
     
  11. laser

    laser Advertiser Advertiser

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    Change the bulb. The 150 watt lamp creates too much heat.
     
  12. swittmann

    swittmann Member

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    Thank you very much :smile:
     
  13. Edtog

    Edtog Member

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    I use a sheet of ND filter, made by Lee filters, and cut it down.
    Works perfectly :smile:
     
  14. L Gebhardt

    L Gebhardt Subscriber

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    Yes, that is the type of filter I was thinking of. I use a 52mm one because it fits my 150mm enlarger lens. To use it on the 80mm I use a step up ring.

    But after seeing your recent posts I would try the 75watt bulb first. It will increase your time by more than a factor of two from the 150 watt bulb.
     
  15. swittmann

    swittmann Member

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    Thank you, L Gebhardt, I think this is the way to go since I need a new bulb anyway and then I will see if I get the times required. If not, I will also get a ND filter.

    Thank you all for your help, everyone.