Thread: M83 rgb
View Single Post
Old 23-04-2021, 08:16 AM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
Join Date: Oct 2007
Location: Hinchinbrook
Posts: 20,623
Originally Posted by ChrisD View Post
I watched presentation on youtube by Dr Robin Glover the author of SharpCaps. Talks about optimum sub times for different Bortle zones. Recommends very short sub times in Bortle 9 to get lots of subs to make it easier for stacking to improve the signal to noise ratio.
After watching this, talking to a few people and re-watching one of Craig Stark old presentations I've come to the conclusion that there's no free beer. The main source of noise is skyglow. I can mitigate that somehow with a filter but the bottom line is that the only way around it is to shoot an "astronomical" amount of subs (100s) to match the same SNR from a handful shot at a dark site.

The argument that shorter subs will yield a better SNR in the stack I'm clearly not convinced because the photon count coming from the galaxy and the sky will proportionally reduce for both. So double the amount of halved subs should be the same as half of subs with double the exposure. The only advantage would be that the SNR in one normal sub or half a sub is the same. So I guess you have less chances of losing a sub and the FWHM could potentially be better as you're guiding for smaller intervals.
Reply With Quote