What is happening to my stacked image?

[jm_rim]

Hi, I'm fairly new to the processing part, as I first recently have had success with getting useable frames.

I have tried to stack both using DSS and APP with a similar outcome. I have attached an overprocessed image where there are clear strange colours. Am I doing something wrong in the stacking process, or I this due to gradient, or are some of the calibration frames to blame?  

Nikon D5300
Dark, Bias, and Flat

Edited January 15, 2021 by jm_rim
Added info

[michael.h.f.wilkinson]

Not entirely sure, but it looks like a gradient due to LP, so try "light pollution removal" under "tools" in APP, to see if you can get rid of them. You simply select at least 5 boxes that don't contain diffuse nebulae (stars are OK, they get ignored), and press calculate. This can help a lot.

[Seelive]

Often a process of trial by elimination can help. Start by just stacking the lights to see the result. Better or worse? Then (say) include the bias, better, no difference or worse? If the latter, then leave them out and repeat the process with the darks or the flats etc. A bit of a time consuming task due to the number of varations you can try, but what else can you do on a cloudy night? 😊

[ollypenrice]

That's not particularly unusual and is, essentially, vignetting. Did you shoot flats? If you did, what is slightly odd is that the vignetting is inconsistent across the colours. Blue seems worse affected than red. Blue has dropped off severely towards the corners as compared with red.

A gradient removal tool in software would greatly reduce the problem but first I'd want to be thinking about the flats.

Olly

[jm_rim]

On 15/01/2021 at 16:57, michael.h.f.wilkinson said:

, but it looks like a gradient due to LP,

On 15/01/2021 at 17:26, Seelive said:

ften a process of trial by elimination can help. Start by just stacking the lights to see the result. Better or worse?

On 15/01/2021 at 19:18, ollypenrice said:

That's not particularly unusual and is, essentially, vignetting. Did you shoot flats? I

 

I'm could not find one specific problem when testing different stacking combinations. However, while assessing my scope I found a massive light leak, which I'm quite sure is causing some of the problems. But if it has affected my flats or light frames (or both) I'm not completely sure of yet. I will try and do some more testing and optimize my scope as...