Stacking issue.

[BillKinn]

Hi all can anyone tell me why I'm getting this distortion after stacking, I shot 72x50 second shots and stacked it with 20 flat 20 bias and 20 dark in Deepskystacker I used 80% stacking.

I'm new to stacking and processing so I'm not sure if this is normal or not. I did try to process the image in Pixelsight but I get a really bright circle in the centre of the image so maybe this is due to the stacking I'm not sure.

Any help would be apricated.

Thanks Bill. 

 

Veil Neb.tif

[Aramcheck]

Hi Bill,
Here's a couple of stretched jpgs from the tif file, which may make it easier for folks to comment. (Saves having to download & modify the tiff).

I'm not an expert, but it looks to me that you have some coma issues, with the the distortion of the stars at the edges / corners of the image pointing towards the centre. Also - as there is some trailing at the centre, you probably should check the individual light frames, as some may have defcets due to movement of the scope during the exposure. This can be caused by gusts of wind, snagging cables, or mount issues.

Also - the flats don't seem to have worked. There's vignetting around the edge, which the flats should have compensated for and a dust bunny is visible to the right (& up a bit) of 52 Cyg.

It might also help to know what equipment you have used.
Cheers
Ivor
PS: You can also try stacking in Pixinsight.

[BillKinn]

Thanks for the info I think it is my flat frames. I was looking at my t ring for my DSLR and noticed that it's cutting the corners of my image, so now looking into getting a bigger one if that's even a thing. 

My gear is a EXOS-2 mount with a Sky-Watcher 200pds and I'm using a Canon 6D which is a full framed. 

I tried stacking is Pixlnsight but it kept rejecting the flats probably due to the issue above. 

I took the flats using backyardESO and the display picture was fully white but when I looked at the canon's display screen I could see a lot of vignetting, I didn't even think to look at that 😬

Still have shed loads to learn, thanks again for taking the time to look.

Regards Bill.