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Old Dec 6, 2003, 3:00 PM   #11
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Default Re: Purple Fringing

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Originally Posted by EdOertel

I have read comments about "purple fringing" and have seen evidence of it in a sample photo from the Oly C750. Can anyone explain what this is?
Fringing of this sort is unfortunately common in Olympus digital cameras (I have two) especially in high contrast situations such as bright sunlight. The reason for it is explained in several other posts in this thread...

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Old Dec 7, 2003, 3:20 AM   #12
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Default Re: Purple Fringing

Quote:
Originally Posted by tedj101
I have read comments about "purple fringing" and have seen evidence of it in a sample photo from the Oly C750. Can anyone explain what this is?
Quote:
Originally Posted by EdOertel
Fringing of this sort is unfortunately common in Olympus digital cameras
It's a misconception that this problem is limited to Olympus cameras...many cameras with longer zooms are affected, and even those with shorter zooms; in the example I gave above the principal example of a camera with a major CA problem is the Canon G1 which is only a 3x zoom camera.
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Old Dec 7, 2003, 5:01 AM   #13
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Default Re: Purple Fringing

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Originally Posted by Mike_PEAT
Quote:
Originally Posted by tedj101
I have read comments about "purple fringing" and have seen evidence of it in a sample photo from the Oly C750. Can anyone explain what this is?
Quote:
Originally Posted by EdOertel
Fringing of this sort is unfortunately common in Olympus digital cameras
It's a misconception that this problem is limited to Olympus cameras...many cameras with longer zooms are affected, and even those with shorter zooms; in the example I gave above the principal example of a camera with a major CA problem is the Canon G1 which is only a 3x zoom camera.
Well, I certainly never indicated that this was limited in any way to Olympus cameras. I said it is unfortunately common in Olympus digital cameras -- and that unfortunate situation is not limited to those with long zooms. It is just as evident in my Olympus with a 3-1 zoom. Having said that, I also want to make the point that it is not all that big a problem either. If it is evident in 5% of the pictures I have taken with these cameras I'd be very surprised.

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Old Dec 7, 2003, 7:25 AM   #14
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BigMac

I agree with speed of light which is the basis for all lenses (ie slow down change direction for different mediums etc...). They are all related, but the key point in chromatic abberation is the index of refraction, which varies for different wavelenghts like @ the edges of a concave lens which split white light much like a prism into multiple colors.

What I questioned was "... different coloured wavelengths travel at different speeds that they don't reach the CCD at the same time..." which in term of shutter speed or CCD sampling rate is several magnitude less than their relative speed difference! The more accurate description is "... they don't reach the CCD at the same place" or focal point which is why IR source has a separate marking on the focusing barrel
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Old Dec 7, 2003, 10:55 AM   #15
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I know very little about Photoshop but I understand that the "PICTURE WINDOW" software from Digital Light and Color has a much better method of editing fringing than PhotoShop. I use this software but it requires some study to learn.
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Old Dec 7, 2003, 6:18 PM   #16
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I think the technique used in Picture Window is similar to that employed in Helmut Dersch's Panorama Tools.
Article on using Panorama Tools plugin in Photoshop to correct CA and other lens errors :

http://www.caldwellphotographic.com/...rFringing.html
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