what causes the purple / blue fringe ?

Discussion in 'Digital Photography' started by digiboy, Apr 4, 2004.

  1. digiboy

    digiboy Guest

    What causes the purple / blue fringe? Many digicam reviews say
    'chromatic aberattion' but I'm not sure I believe this as I always
    thought chromatic aberation is when a lens gives a different point of
    focus for different wavelengths of light ie the aberation give _depth_
    problems, not _lateral_ problems.

    Also the 14n suffers, when the equivalent film cams and lenses do not.

    So its something in the Bayer sensor grid / filter?

    Ideas and comments...

    digiboy, Apr 4, 2004
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  2. (digiboy) wrote in @posting.google.com:
    First idea : search old posts on google. This topic has been
    discussed lots of times here and also elsewhere.

    The opinions on this vary very much.

    Roland Karlsson, Apr 4, 2004
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  3. digiboy

    John Navas Guest

    [POSTED TO rec.photo.digital - REPLY ON USENET PLEASE]

    Microlenses and small photosites.


    Purple Fringing

    Purple fringing, also known by its technical name bichrominance [or
    birefringence], has been the source of much discussion among
    photographers. It is quite distinct from chromatic aberration -
    though both are often seen under the same circumstances - namely
    strong back light areas of high contrast, such as shiny chrome or
    back-lit tree branches.

    Though there has been much debate about what causes PF (it now
    appears that microlenses on the surface of the sensor may be the
    major cause, especially when combined with small photo-sites, such as
    the 3 micron sensors on the Sony 8MP chip design), there is little
    agreement about how serious a problem it is. Some photographers find
    it everywhere, others are rarely bothered by it.
    John Navas, Apr 4, 2004
  4. digiboy

    Jack Mac Guest

    Go here for an explanation of CA:

    Jack Mac
    Jack Mac, Apr 4, 2004
  5. Roland Karlsson, Apr 4, 2004
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