Visible problems in the image-output with disturbing error patterns and artifacts

[per_lovren@yahoo.com]

Visible problems in the image-output : disturbing error-patterns and artifacts :
Small disturbing "error-patterns" occurs in the image when scanning medium format negatives using Epson V750 PRO and silverfast Ai .
The disturbing patterns are very colorful and appears in vivid colours". (Almost like spectral patterns)
The shape of the "pattern" is based on a detail in the negative = Like a sampling
The location and size of the "error-patterns" varies between different scanning attempts of the same neg.
Sometimes they are clearly visible and other times harder to detect.
I do not run any other computer programs parallel to Silverfast during scanning.
I do Not touch the scanner during operation and usually leave the room.
I use very high scanning resolutions. (6400 dpi etc) but the problem also occurred when I tried lower resolutions.
I have tried cleaning the scanner, rebooting the computer, using different software versions of Silverfast but so far to no avail.
I have asked Epson, but they dont know what is causing the error-patterns and have no solution.

I will be happy for any advice on how to solve this problem !
Please see attached file !

Kind Regards !
Per

[LSI_Ketelhohn]

Dear user,

Does that issue follow the direction the sensor and lamp move?
It looks like it could be caused by dirt on the lamp or sensor.

This is likely some effect occurring directly in the scanner.
The strange thing is the blue/cyan/yellow/red pattern. That also could point to some kind of electronic issue.

Kind regards,
Arne

[Jossie]

Hello,

as far as I can tell, this is most likely due to a stepper motor problem. A similar looking example is given in the reflecta DigitDia manual. Extreme examples may be found here and here.

Hermann-Josef