California Nebula at 135mm

[FenlandPaul]

This is my second attempt at a widefield emission nebula, this time the California Nebula.  

For those interested: 201x 45s exposures at ISO800 with a modded Canon EOS450D, Samyang 135mm lens at f/2.8, all on a SkyWatcher Star Adventurer tracker. Processed in DSS and PS and cropped.  I'd initially had about 50% more subs than that but some were ruined by cloud and others by my youngest son putting the back garden light on!!

I'd really appreciate any feedback / tips - keen to learn more about this amazing craft!! 😀

Thanks, Paul.

Edited November 23, 2020 by FenlandPaul

[happy-kat]

Nothing leaps out, lovely image, great star shapes, super.

Was that with no calibration files too?

[FenlandPaul]

2 minutes ago, happy-kat said:

Nothing leaps out, lovely image, great star shapes, super.

Was that with no calibration files too?

Thank you.  I did darks and flats as well, which I've found I definitely need to do with this camera / lens combo on anything remotely deep-sky-y.

[happy-kat]

There's also a long thread on imaging using that lens

Dark flats are super quick to take as well

[Kyle Allen]

Lovely image but the stars look big on the left side (like they are ever so slightly out of focus) compared to the right.

[FenlandPaul]

41 minutes ago, Kyle Allen said:

Lovely image but the stars look big on the left side (like they are ever so slightly out of focus) compared to the right.

Thanks Kyle.  It looks like something has crept in during processing.  The original unprocessed stack (below) doesn't seem to have the same issue (to my eye - unscientifically) but it looks like it's come in when I tried to deal with the gradients.  🤔

[Kyle Allen]

Zooming in close, the right half looks fine but towards the left edge the stars seem to have a sort of flare coming off them. I’m no expert but could it possibly be coma? I’m sure someone here will know! 🙂

[wxsatuser]

10 hours ago, Kyle Allen said:

Lovely image but the stars look big on the left side (like they are ever so slightly out of focus) compared to the right.

It's not quite right to the left, looks like slight coma top left even in the unprocessed stack.

These Samyangs can vary a bit, mine has a very slight odd corner but not as bad as that.
It's a modded camera so may be something not so perfect about that.