Lens Problem

Discussion in 'Large Format Cameras and Accessories' started by David Vickery, Apr 19, 2003.

  1. David Vickery

    David Vickery Member

    Sep 7, 2002
    Central Texa
    ULarge Format
    Hello, I have a problem with this lens and I wanted to see if anyone else has had similar problems with any of their lenses. On the print I will have a central area of about 2.5" in diameter that is of slightly higher density on the film and unsharp compared to the rest of the film. If all movements are centered then this area is circular and in the center of the film. If movements are used then it is off center accordingly and eliptical. It is not a distinct area but just annoyingly fuzzier and lighter in the print. I might be able to attach an example tonight if that would help to explain my description. Thanks.
  2. Ed Sukach

    Ed Sukach Member

    Nov 27, 2002
    Ipswich, Mas
    Medium Format
    This sounds like an incorrect assembly problem - either one of the elements "reversed" or incorrect element spacing. Is this a change in lens performance, i.e., after lens or shutter repair or maintenance, or has it been like this since new?

    Is there any evidence of clouding or fungus, or cement separation?

    When you say that the area affected is "off center and elliptical when movements are used", what movements are in question ... "tilts" and "swings", where the film plane is no longer parallel to the center of the optical axis, or do parallel movements - "rises" and "falls" - alone cause this effect (which would really baffle the hell out of me)?

    *Some* fall-off (the extremes of the field receive less light than the center) is to be expected, but the "out-of-focusness" in the center - CAN the center area be focused? - seems to be out of the ordinary.