Rainbow effect on scans

DeleteYourself

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Rainbow effect on scans

#1

11-15-2005, 07:26 PM

I'm filling in at my work for prepress at the moment, since I'm one of the only ones who knows how to work our 5 year-old scanner (a Screen Cezanne). I know, procedurally, how to scan images, but I'm not very well-versed in troubleshooting.

I'm wet scanning positive film and I seem to be getting a rainbow effect in certain parts of the scan. Originally I thought it was due to cleaning residue on the surface of the scanner, but I've been very carfeul that last few times to thoroughly dry it off.

Could this be happening due to the fact that our scanner is getting old? What else could be causing this?

Here's an example of what I'm talking about:
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rickself

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#2

11-15-2005, 07:49 PM

Can you turn your film around and rescan to see if the scanner is having trouble with a particular x-y position? That would eliminate the film or the scanner.
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DeleteYourself

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#3

11-15-2005, 07:57 PM

I've rescanned several times in different places, so I don't think it's the the position. It could have something to do with the lens perhaps? I just don't know.
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rickself

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#4

11-15-2005, 08:16 PM

have you tried emulsion up, as well as emulsion down on the glass?
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Magnus

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#5

11-15-2005, 08:18 PM

Todd, is it happening in different parts of the image, or just on those shutters?
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DeleteYourself

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#6

11-15-2005, 09:04 PM

I haven't tried emulsioin up, I assumed that would just produce a dull scan. No? I'll try if you think it's worth a shot.

Mag, on this particular image it's happening on just the shutters, but it happens on all kinds of images. I have noticed, though, that it tends to happen more in complicated areas, or areas that have lots of light reflection (such as chrome or a light fixture, etc).
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cjoe

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#7

11-16-2005, 01:16 AM

it looks like chromatic abberation caused by faults in the lens of the camera/imager,
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DeleteYourself

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#8

11-16-2005, 02:16 PM

Thanks, cjoe. I suspected it was a mechanical problem, but I wasn't sure what.
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