Lines in my M45 image

[Dean]

Hi can anybody tell what has caused these lines and what I can do to get rid of them? Also there seems to be dark edges around the smaller stars. I have never noticed these effects before so any advice would be great. The image is a stack of 22x30sec subs at ISO 400 and 16x30sec ISO 400 darks and stacked using deepskystacker

Thanks Dean

[narrowbandpaul]

try without darks....

it could be column fixed pattern noise....(dont ask)

[jgs001]

DeanDReam, I think Lightbucket found something like that with the latest DSS and found that using kappa sigma (I think) stacking of the darks solved it for him.

[Dean]

Thanks narrowbandpaul here one without darks.

[narrowbandpaul]

hmmmm....

do you apply flats?

flats should remove FPN if done right.

take about 30 flats, add these to the mix.

the darks havent helped the lines so arent the source of the problem.

are you using bias frames.

flats would be my first point of call

[Tim]

It has been a while since I used my 350D. At a setting of iso400, 30 secs wont give you too much in the way of fainter stuff, but I see you have tried to make the most of what you have. I'd say you have just gone a little too far with it.

Of course, you can stretch it to destruction to bring out the nebulosity, but you will also highlight all the fixed noise elements that wouldnt normally be seen with standard stretching.

To get good detail that is really very faint, longer exposures are necessary. You may get a smoother result with 100 x 30 secs, but if possible try for 25 x 60 secs, and use iso800. Any increase in noise from using iso800 will be swept away with stacking when you have 25+ subs to use.

Hope that helps a little.

TJ