DeepSkyStacker help

[dynasty99]

Hello,

I am having trouble with DSS and was wondering if anyone could help my problem

I am working on an image of M31, from 52 subframes. There is a drift between the frames, and DSS does not seem to "see" it, or atleast does not align the frames when stacking.

So you can see what I mean, I have attached 3 images:

- a subframe near the start of imaging

- a subframe near the end of imaging

- the stacked image (this one of 45 frames I think, but adjusting my rejection cutoff has had no effect)

Of course the frames I am stacking are RAW files, just showing you jpegs for convenience.

Has anyone run into this before? Any suggestions for settings for me to try? I have fiddled with different stacking, and aligning modes, but the stack has always come out with the same problem

Thanks a lot!

[dynasty99]

Update: I solved my problem! I can't find the delete button, but mods please delete or do what you will with this thread.

Thanks anyway!

[martin_h]

Just out of interest, maybe to others who may come across the same problem, what was the solution?

[dynasty99]

This is kind of an obvious solution now, so I feel a little foolish for asking in the first place, but...

My star detection threshold was set too low, and DSS was picking up noisy pixels as stars. That presumably random distribution of stars fooled it to thinking the frames did not move, and just stacked them as such.

I used the star editor tool when clicking on individual light frames to see what was being identified as stars (noise), and adjusted the star detection threshold until it was picking only actual stars (26% turned out to work).

In any case, after a quick 20 minute stab in photoshop to improve the levels, I attached what I have for anyone's curiosity. Still lots to learn at every stage, but it's a start

[Jannis]

Looks like a good start you're on to there.

But your image seems to be slightly out of focus, that's probably why DSS didn't detect the stars properly at the defaulth settings (as it expected the stars to cover a smaller amount of pixels, and therefor detected the noise as stars instead).

I recomend to use a batinov mask next time for focusing, it will make it a lot easier, and you can be sure when you've captured all the pictures that the result will be good after stacking them

how did you take these pictures, btw?

[dynasty99]

I took them using a Nikon D3100 at prime focus on a Celestron CGE1400, EQ tracking but it was clearly a bit off. As I am waiting on a remote release cable, I was limited to 30s exposures. It is not my telescope (I wish..), so I do not have a Batinov for it yet; I will need to see if my method for my homemade 6" one will scale up well to 14".

Thanks for your suggestions