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Old Nov 14, 2003, 5:01 AM   #1
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Default New A80: Blue colour fringing and white balance error.

Hi all, The A80 is Canons newest Powershot model. They have fitted a physically larger ccd and put the Mp's up from 3.2 to 4Mpix.

I took several daylight shots in my garden, 200ASA, 1/125 at f5.6, wide and mid zoom, highest quality, soft sharp.

Overall there is a consistent blue white inbalance which is correctable in PS. However at 100% mag, there is a horrible blue smear on verticals, and in particular tree trunks and outlines against plain sky. I mean, the smear can be as much as half a narrow branch or tree trunk.

If I open up an image and look at the separate RGB component images, there is definitely a wide overlap on the blue component channel.

Is this something that all Powershots do, or could I just have a bad camera? Anybody else seen this on say the A70? Is there something in setup I might have missed? Thanks VOX
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Old Nov 14, 2003, 1:02 PM   #2
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This is a well known issue concerning "blooming", CA, purple fringing or whatever you wish to call it. It is really blue but people refer to it as purple. It only happens with my A80 in high contrast shots. I just fix it post processing. Since I very seldom view pics at 100% zoom so it does not bother me very much.

I read it is related to the latest 4.0 megapixel CCD in relationship to the camera's lens capability. Canon, like most digital camera manufacturers do not manufacture CCDs. Sony is one of the 3 or so companies that makes CCDs.

I have researched it in the forums at http://www.dpreview.com/forums/forum.asp?forum=1010 and there appears to be no real cure for it.

Seems as though there is no perfect camera, especially at the price you can get an A80 for.

http://forums.dpreview.com/forums/re...essage=6546072 lists a free app to help remove purple fringing.


If you shoot a lot of high contrast shots or view under high magnification the 3 megapixel camera may suit your needs better.

Do a search for "purple fringing" (without the quotes) at http://www.dpreview.com/forums/forum.asp?forum=1010 and you will find a lot more info on the subject from people who are much more knowledgeable on the subject than I am.

The subject has been beaten to death, IMO.
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Old Nov 17, 2003, 4:42 AM   #3
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Flylow, thanks for your feedback. I did some more research and concur about the 'well known problem'. I also found the Photoshop fix, which replaces blue with grey. However, when I saw this on the A80, I thought, 'why should I be accepting an artefact which I can do nothing about'? Hue, colorimetry, white bal and levels can all be sorted reasonably well afterwards - but if you get CA, you're stuck with it! My other consideration was, what's the point of having 4Mpixels, when the one's that are needed to give edge detail, can smear as blue? When I saw the result of the overlayed blue image on Green, I saw the light so to speak!

My 602 rarely shows this problem to the same extent - but then it physically has larger glass than the Powershots. In the end I've decided to avoid the Powershot compacts and look at Minolta and Nikon compacts, who claim better lenses to reduce CA.

In the end, picture quality is still probably down to lenses and ccd for the price paid. All the software features in the world will not improve image quality if there are registration or geometry issues in this marriage. Unfortunately, many digicam buyers are looking at style/size/weight/Mpixels - and newer cameras following this design trend may just be sacrificing compactness for image quality -what do you think? VOX
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Old Nov 17, 2003, 3:43 PM   #4
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Quote:
Originally Posted by voxmagna
-what do you think? VOX
I think the A80 is awesome camera, it is not perfect. Some G5 owners notice CA too. CA is easily fixed so I do not think it is that much of an issue. It does not affect the majority of shots. I use 100% magnification during processing not for viewing. The A80 more than adequate for my personal needs. I think the S400 is too small for my hands, I do not care for the S45 and S50. I do not need all the features on the G3 and G5. I have not tried Minolta digitals but I owned a Nikon 3500 and I much prefer the A80.

I think the output of a digital camera is more like a negative. A digital camera is not a Polaroid. I expect to do processing.

Other peoples needs and wants are different than mine but I feel that no matter what camera you buy there will be somethings that could have been improved upon. I think that today's digital cameras are great and the next product cycle will always bring something better. I can easily live with the A80 and it's pros and cons until I upgrade in a year or three.

Buy the camera that best fits your needs.
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