In some of my recent scans I discovered bands in the sky.
They do not appear on the negative. I proved that by putting the negative in the opposite way in the holder,
with the sky in the other direction.

I use an Epson Perfection V700 and Vuescan.
The scans are from 6x7 Portra 160, scanned at 48 Bit RGB, with 3200 dpi, Number of samples 3, output as raw file.
Scanner moved from the left to the right.


Here's an example picture (bands appear on the top edge):

Verlassene Fabrik #33 by andi_heuser, auf Flickr


What could be the cause for such bands?
Though they are only slight I would prefer to avoid these.

Andi