Strange lines on scans

Hi guys, any idea what the lines are in these lab scans, they were done on a noritsu and are most noticeable in the blue sky. I had already scanned the negs with a digital camera at low res at home and the lines weren't on those.

Thanks
Ben

Nice photos.
The lines/bands are fairly obvious; in case people have trouble seeing them, they show up more clearly when contrast is boosted:



My first guess would be that these are caused by fluctuations in the output of the light source in the scanner.
Such problems do happen; see e.g. here: https://www.minilabhelp.com/index.p...led-light-source-uneven-possible-led-burnout/
This is something you should discuss with the lab you used for these scans so they become aware of the problem. They may have to do calibration or even repairs on their scanner.
Btw, I suspect that the cause of the problem is different from the link I gave above because the variations in density appear to be perpendicular to the length of the film. This suggests light source fluctuations over time, and not a difference in output across the width of the light source. The first possible underlying cause that comes to mind is a light source power supply problem. Basically hum/noise; based on scanning speed and the distance between the bands, it should be possible to work out the frequency - it wouldn't surprise me if it turned out to be 100Hz (twice AC grid frequency).

It's a known problem on Noritsu scanners. It shows mostly on very dense negatives (or dense parts).

Presumably related to the weakening of light source, since not all Noritsu scanners exhibit the problem.

Your lab introduced these artifacts via their scanner. I agree that you should have a talk with your lab about this.