Print Vignetting

Discussion in 'Enlarging' started by PhotoPete, Dec 21, 2005.

  1. PhotoPete

    PhotoPete Member

    Messages:
    320
    Joined:
    Aug 23, 2005
    Location:
    Waltham, MA
    Shooter:
    Multi Format
    I am hoping that someone can help me with a darkroom printing problem I am having. I am using a Besseler 67c and a 75 mm Nikkor lens and am experiencing significant light drop-off towards the corners of the print. I am printing 6x7 negatives and have the 6x7 head in place. I have stopped the lens all the way down, but the problem persists. The negatives are correctly exposed all the way to the edges. Could this be the product of a failing bulb? I have previously been able to make prints from these negs without difficulty. Any ideas as to the cause or a possible resolution would be welcome.
     
  2. Nige

    Nige Subscriber

    Messages:
    2,133
    Joined:
    Sep 8, 2002
    Shooter:
    Multi Format
    Have you made prints from those negs AND that lens? No idea of the specs of that lens but you might need one with more coverage, eg a 90mm
     
  3. rbarker

    rbarker Member

    Messages:
    2,222
    Joined:
    Oct 31, 2004
    Location:
    Rio Rancho,
    Shooter:
    Multi Format
    A 75mm lens is a bit short for 6x7, so you may be suffering from coverage problems. An 80mm lens is "standard" for 6x6, and 90mm is usual for 6x7 or 6x9, depending on the lens design. Thus, you may need to either get a longer lens, or adjust corner exposure to compensate. Check center versus corners with a light meter (without a negative in the holder) to check relative brightness. It should be the same across the whole area. You should also verify that you have the appropriate condensor for 6x7.
     
  4. Tony Egan

    Tony Egan Subscriber

    Messages:
    1,194
    Joined:
    Oct 29, 2005
    Location:
    Sydney, Aust
    Shooter:
    Multi Format
    If you are printing more than about 85% of the negative i.e. not cropping much, a 75mm lens is inadequate for 6x7 negs. I regularly print 6x7 and have had similar problems with 75mm. Its sounds like a lens coverage issue. I use a 105mm lens for most of my 6x7 negs.
     
  5. Konical

    Konical Subscriber

    Messages:
    1,709
    Joined:
    Jun 1, 2003
    Good Morning,

    I also have a 75mm Nikkor; its coverage is inadequate for 6 x 7, although it's great for 6 x 6. As already indicated above, a 90mm works very well. That focal length is a little harder to find on the used market than a 105mm, but a while back I bid successfully on E-Bay for one (Rodenstock Omegaron) which delivers excellent results.

    Konical