On very sky-heavy photos I seem to often get banding just in the sky part of the image. As far I can tell using an 8x loupe, the bands are not there on the actual negative. The fairly narrow vertical bands can be seen in the sky of this photo: (cinematic log, auto avg WB, no other adjustments)
Unconverted negative:Banding on sky-heavy photos - Album on Imgur (new user; can only embed one image)
As I bring the brightness of the image down, the banding appears worse. The effect is more pronounced when I’m scanning 645 negatives compared to 35mm. I tried exposure-bracketing the same negative to see if that would solve it and the banding is still visible. I do not think my light is causing the issue. Here is an image of the light source focused where the film sits in the holder: Banding on sky-heavy photos - Album on Imgur (new user; can only embed one image)
I’m happy to share the dng if it is useful.
Mirrorless scanning with Fuji X-T30, Sigma Macro 50mm EX DG PK mount, Raleno PLV-S192 light, 3d Printed 120 film holder, copy stand