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Thread: Sony A700 camera: How to Eliminate Fringing

  1. #1
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    Sony A700 camera: How to Eliminate Fringing

    What can I do about colour fringing with long lenses?

  2. #2
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    Re: Sony A700 camera: How to Eliminate Fringing

    If by "fringing" you mean chromatic aberrations (CA), then this can be dramatically reduced in software. Photoshop CS's Camera RAW converter has a built in CA reducer, for example, which you can tune during the development of the RAW file. CA is best identified by the fact that it is usually cyan/magenta in nature, and increases in intensity further from the center of the image.

    If by "fringing" you mean "purple fringing" or "blooming", then this is a much more difficult problem to confront. You can either avoid extremely contrasty compositions (dark tree branches against a bright sky, specular highlights of metal surfaces, etc), or sometimes using a much smaller aperture can help (f/8 or f/11+). If it's really problematic, you might even need to use a different telephoto lens entirely. Purple fringing is different from CA in that it is nearly uniform throughout the image, both in the corners and in the center.

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    Re: Sony A700 camera: How to Eliminate Fringing

    Photoshop's camera raw, or Lightroom have sliders to correct both cyan/magenta and blue/yellow chromatic abberations -- think of it as a lens problem -- and they work by adjusting the size of the colour channels.

    Think of purple fringing as a sensor problem, with individual photo sites being overloaded. There is a defringe control in LR, and it may help to reduce the fringing -- and perhaps combined with use of the chromatic abberation sliders.

    If there is an easy answer to this, I have yet to find it.

    A theoretical possibility might be to reduce the amount of light falling on the sensor by a combination of higher ISO and shorter exposure -- I haven't tried this -- and it will probably lead to noiser pix -- swings and roundabouts.

  4. #4
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    Re: Sony A700 camera: How to Eliminate Fringing

    Thank you for help with above problem. Shows up with contrast of birds against blue sky and dark trees against same. Two fast replies. Much appreciated. ---conmor

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