Canon 70-200 f/4L IS chrom. aber. WTF?

Discussion in 'Digital Photography' started by jwt, Apr 12, 2008.

  1. jwt macrumors 6502

    Joined:
    Mar 28, 2007
    #1
    Anyone ever seen chromatic aberration on the said lens like this? The attached file is a 1:1 crop of a region. Regions of his shirt are clipped, but that's a sensor issue. Chromatic aberrations are a lens issue, right?
     

    Attached Files:

  2. robbieduncan Moderator emeritus

    robbieduncan

    Joined:
    Jul 24, 2002
    Location:
    London
    #2
    I don't have the IS version but I see a tiny amount of CA in extreme light conditions with mine if focus is not right on. That looks pretty soft...
     
  3. anubis macrumors 6502a

    Joined:
    Feb 7, 2003
    #3
    Looks more like purple fringing to me. This is not purely chromatic aberration and has more to do with the sensor (blooming, etc.) There is disagreement among the photography community as to what exactly causes purple fringing.

    Happens when there is an "overexposed" area right next to an underexposed area (i.e. areas of high contrast). The purple fringing goes down if you use a UV filter and keep the f-number at f/4 or higher.
     
  4. ChrisA macrumors G4

    Joined:
    Jan 5, 2006
    Location:
    Redondo Beach, California
    #4
    Looks to me like an image processing artifact. Where you shooting JPG format? I think it has to do with Bayer interpolation across the white/black boundary. If this is a raw image it would be good to see if other raw processors have the same problem.

    If it were a lens issue then the fringing would have been in a radial direction away from the center point of the image. This follows the line and is either a sensor or image processing artifact.
     
  5. jwt thread starter macrumors 6502

    Joined:
    Mar 28, 2007
    #5
    The image was shot in RAW. I shoot a lot of landscapes this was the first time I've ever seen purple fringing on this lens. My 17-85 USM IS does it all the time, and that's why I don't use it much.
     
  6. mcarnes macrumors 68000

    mcarnes

    Joined:
    Mar 14, 2004
    Location:
    USA! USA!
    #6
    It's customary to start threads like this with a photo of your cat. You're breaking the tradition.
     

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