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Old Jan 7, 2003, 6:10 PM   #1
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Default Metal shows "colors" on Coolpix 2500

I took a photo of a building that had a metal shiney smoke stack, that stack showed some color bands in it, not very distracting, but still can be seen.
I have taken a lot of photos with the 2500 and never seen this on this camera, I have seen it on my El-cheapo Aiptek pencam when I photographed cars that had some chrome, the chrome showed up as color bands. I felt that was because the Aiptek pencam used a "CMOS" instead of a "CCD" like my Nikon 2500 uses.
Has anyone run into this strange thing with shiney metal?
I posted this same question on another forum, but got no responce.
Perhaps the great folks on this forum could help answer my question.
I would send the picture, but I do not have a website to hold photos.
Thanks in advance.
Bill
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Old Jan 7, 2003, 7:44 PM   #2
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Bill

Could it have been the angle on the sun that created a rainbow effect?

Phil
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Old Jan 8, 2003, 2:55 AM   #3
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Thanks gibson3620, I don't know, it could be the angle of the sun, but I guess I will have to retake the photo perhaps with my 35mm film camera and than with the Coolpix and see if the colors show on both cameras.
If the colors show only on the digital camera, than I would say it is the nature of the beast(digital) :?
Bill
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Old Jan 8, 2003, 3:30 PM   #4
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The type of banding you describe is often due to 'aliasing' when digital sampling produces stuff it should't which gets mixed up with stuff you want (My crude definition). You will see it sometimes on your monitor and printers can do it with fine detail - so you're sure it's on the cam file?

I would imagine that shiny reflective surfaces could overload sensors, when they will produce the stuff you don't want. A test is to severely under expose and or de-focus and see if the prob goes away. You could say 'It's the nature of the beast'.

Cheers, VOX
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Old Jan 8, 2003, 5:32 PM   #5
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Thanks again guys, I appreciate the information.
Yes VOX, it is on the JPG right out of the camera.
How do I de-focus the 2500? do you mean retake the photo?
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Bill
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Old Jan 8, 2003, 5:46 PM   #6
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I don't know the 2500, but my comment is a general one for picture aliasing. If it's an interference pattern related to the oveloading of the sensor or detail, a general test is to reduce high frequency detail - by defocussing, even slightly or try changing zoom setting, or try the same shot at a different resolution. Overload is obvious - underexpose. I'm not saying these are ways of shooting! - only a means to change what the ccd circuits see, to prove if this might be a processing artefact produced in the cam.

I sympathise that these problems can be frustrating - I found something similar with a wide-angle adaptor, which I'm convinced were glass reflections, but I couldn't see the problem until I put the pic on my pc monitor. I've not seen it since, but then very bright sunshine in UK doesn't come back for a few months!
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