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Old May 10, 2007, 4:33 PM   #1
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What causes purple fringing? Do all digicams purple fringe?

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bvm
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Old May 10, 2007, 5:11 PM   #2
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Chromatic aberration (CA). It's a lens thing. Its caused the camera lens elements not having the same refractive index and therefore not focusing the different wavelengths of light onto the exact same spot. Usually zoom lenses are more prone to exhibit CA, but some lenses have little or no CA(in general, read EXPENSIVE, well designed dSLR lenses), others have a lot. You can google chromatic aberration and find a ton of information and diagrams.
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Old May 10, 2007, 5:39 PM   #3
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Biff vonMises wrote:
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What causes purple fringing? Do all digicams purple fringe?
Chromatic Aberation is a blue glow on one side of a high contrast image, and a red glow on the other. Here's an example. Is that what you're talking about?
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Old May 10, 2007, 8:44 PM   #4
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When a lens is designed the engineer decides what range of colours that will be corrected. The broader the range the more expensive the lens!

See Chromatic Aberration for a quick explanation.

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Old May 10, 2007, 9:34 PM   #5
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You also hear people talking about "blooming" which can have a similar appearance, but blooming is caused by sensor overload, and can happen anywhere on the scene, while CA is more commonly found on the peripheries.

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Old May 10, 2007, 9:59 PM   #6
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Actually there is a little guy with a purple crayon inside your camera.
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Old May 10, 2007, 11:25 PM   #7
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He sure gets around, 'cause he's in my camera too...
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Old May 11, 2007, 2:46 AM   #8
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He must be a pixie, because he sometimes leaves annoying pixie dust on my sensor as well.
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Old May 11, 2007, 7:30 AM   #9
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tjsnaps wrote:
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Actually there is a little guy with a purple crayon inside your camera.
I've seen him. Kinda looks like Barney the dinosaur, but is really, reallysmall.
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Old May 11, 2007, 4:18 PM   #10
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If I give him a black crayon, will he increase some of my shadow details?
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