Does any Nikon 17-55mm user encountered this problem?

Discussion in 'General Technical Discussion' started by daodang, Nov 23, 2005.

  1. While doing some corner sharpness tests with my newly acquired 17-55mm, I notice the uneveness in light falloff
    on the frame edges. The light falloff is more important on the right side than on the left side.

    The same uneveness appears at every focal length. It's evident at f/2.8 and tends to diminish with smaller apertures (it almost disappear at f/8)

    Here's a sample of the phenomenon.
    35mm, f/2.8 - NEF converted as is to Jpeg by Nikon View -no sharpening, low contrast.
    52677088.gif

    What can be the problem?

    Thank you.
     
  2. Dao,
    This virtually dissapears at f4 and above. It is normal. there is some information regarding this in the december issue of popular photography coincidently.
    Dave
     
    Last edited by a moderator: Nov 24, 2005
  3. Dave,

    a great thank for the information. Appreciates a lot your help in this matter.
     
  4. nfoto

    nfoto Guest

    Could be an indication of a slightly misaligned element in the optics making the image not perfectly centered on the optical axis. If this is the case, you should be able to detect an increase in CA on that same side of the frame.

    A further test to this end would be to take similar pictures at three different focus setting (infinity, close focus limit, 2-3 m) and see whether the darkened areas change in position. If they don't alter the position, the fall-off is likely not caused by the optics and might originate within the lens mechanism itself. Use f/2.8 for these shots.
     
  5. Hi Bjørn, a great thank for input. I will do the tests this weekend.
     
  6. moffo

    moffo

    576
    Oct 20, 2005
    Central TX
    Be sure and let us know what you find -- I'm very sorely tempted to pick up a copy of this lens...
     
  7. Update About This Issue

    I have done several test shots following Bjørn's suggestion (both indoor and outdoor).

    1.- I visually inspect the shots and can't detect any increase in CA on the right side (the one with darkened areas)

    2.- The darkened areas don't change position.

    So the fall-off isn't likely caused by misaligned optic. I will send the lens with the test shots to Nikon to see what they have to say about this issue.
     
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