What are these dark marks on my images?

[lukebl]

As I've mentioned on another thread, I'm struggling a bit with my Atik383L+ which is a bit of a disappointment after my old 428ex and even my vintage SVHF-H9.

Can anyone exlpain what these black lines are on this stacked image? This is about 50 frames with darks and flats stacked in DeepSkyStacker. I can't see anything untoward on any of the individual flats, darks or lights.

 

[david_taurus83]

Did you calibrate the darks with bias?

[lukebl]

13 minutes ago, david_taurus83 said:

Did you calibrate the darks with bias?

No I didn't take any bias frames. They've never seemed to make any difference before, but perhaps I'll give it a go.

[vlaiv]

No need to take the bias if you took darks that match in exposure length.

One of the subs or multiple have either bad column kind of artifact or row of dead pixels or similar.

Softer edges are due to subs alignment and bilinear interpolation that DSS uses.

If it is only single sub - sigma clip stacking should get rid of it - but it can be present on all the subs - in that case you need to "interpolate" defective pixels.