Hi Alex
I would use ImagePlus' grade tool for sorting out the best frames to stack. Maybe accept the best 10%
On short exposure/high gain topic I have followed Łukasz Sujka on Astrobin and he has posted pics of PN taken with these techniques. Really good stuff.
Heres a link to a pic of his
https://www.astrobin.com/418782/
I do remember he said he would check even 800 frames individually to get a decent stack.
Here's what he reckons/writes
<<Welll, It's quite difficult to find some tutorial.
But in general there is few important rules which I think are the most important:
- camera with low readout noise (1eV-2eV or less) - ASI 178, 183, 290 - cooled versions
- bigger aperture 8'' minimum. 10'' is ok, 12'' or more really nice
- a lot of subs - 300 is absolute minimum. Good standard is 1000. But of course more is better
- high gain to achieve lowest redout noise as possible (80-85% is what I usually use)
- short subs - usually below 10s. But less is better
- stacking in Siril or Autostakkert3
- processing like normal photos with more agressive stretch>>
GlennB