Yellow lines when scanning

[Tom Schaefer]

New to scanning.
I'm Scanning a 4x5 at approx 500% using a Microtek M1 with
Silverfast at 4x sampling. When reviewing the scan I noticed
These lines. these are evenly spaced on the scan.
They are not in the chrome. I double checked and they
don't appear on a single pass scan either. Am i doing something wrong

Thanks
Tom

[Gary Beasley]

Actually the sample you posted doesn't show anything on my monitor. Are you sure it's not just an artifact of your video card? I've seen it happen with some programs when zooming, although the artifact is not actually there.

[Jon Shiu]

I can see the yellow lines on my monitor. Is the reason your using multi-sampling to get rid of noise in the sky?

Jon

[Tom Schaefer]

No, just trying to see if more scans worked better.
It is really enlarged to see the yellow lines.
I noticed them when I was checking for dust.
Here is the image.
Thanks
Tom

[Jan Nieuwenhuysen]

Looks like the same problem I experienced, see my previous post: http://www.largeformatphotography.info/forum/showthread.php?t=36285

The difference being that my lines were blue (only showed up in the blue channel), yours are yellow (show up in both green and blue channels I presume).

I never got an answer to my post, but figured the following:
- defect in blue channel. CCD related maybe?
- extremely fine parrallel scratches in the film base and/or mylar foil (FYI: I wet scan).

When I changed to a new batch of mylar the problem was gone. I later put a piece of used mylar under the microscope and found parrallel scratches. I found this conclusive.

I suppose these scratches are either production related, or caused by my own handling (sliding a new sheet of the stack), although I do not think I could pull a sheet so darn straight ahead even I intended to.

Based on this:
In case you use scanning (wet mount) foil such as mylar I would suspect fine scratches in the foil to be the culprit.
Else, ditto in the film.
If neither I would suspect CCD problems.

[eric black]

I know what you are talking about- I get these when I do drum scanning-they show up sporadically and I typically either do the scan again or get rid of the aberrations in photoshop if they are small and not located in a busy part of the picture. I have heard they are related in my case to dust on the CCD or in the light path in general during the scanner calibration steps- a good cleaning should help- seek help if this task is beyond your abilities though.