Quote:
Originally Posted by Camelopardalis
No rigor intended, more curiosity about when the noise becomes largely unobjectionable. Of course, that's subjective...
I have a few targets in the hit list that are fainter than the usual suspects I've been going for, so I've been looking for a yard stick really. The fainter targets will need more total exposure time to have acceptable noise levels when stretched, so it'd be useful to get a feel for what SNR/noise estimate I'm after.
|
Dunk,
Why not make some measurements on a small area of an image you already have that's just around your level of minimum acceptability for noise. If you can figure out how many photons you need to capture in each pixel to get to that point then you can make inferences about future targets on the basis of a few sample subs.
Hint: previews, the Statistics process and PixelMath will do everything you need along with the understanding that shot noise is n^0.5 if you capture n photons (in a single sub or a whole stack) and SNR is n/n^0.5 = n^0.5. You can ignore other sources of noise so long as you're doing subs that are sky limited (and if you're not you should be!)
Ken might not believe me but I do take a fairly rigorous approach to SNR when I'm chasing very faint features. The jets of NGC 1097 would be a good example.
Cheers,
Rick.