So this was another teaching moment for me in my astro journey
Been using 0 gain on the 294mm for a while now but have only really been taking broadband for stars, so wasnt really concerned about resulting noise in stacks, and wanted to keep sub numbers/gigabytes down.
Carry this on into actually having a go at a broadband target and learned the hard way that the read noise of the 294mm in 2x2 nil gain mode requires 'substantial' exposure to swamp it. I did not do that and ended up underexposing in this respect. That said, I couldnt really increase sub time further, as I was already hitting the point of noticeable star bloat.
Thanks to really effective and simple to use noise reduction tools these days, the main impact was that I lost details I should have been able to tease out further in post, particularly background detail. Gradient control too makes you want to drink excessively. Yes, I dithered, 15px. Didnt help much!
Anyway, the take away I wanted to share with others with all of this is if you have the 294, in bin 2 mode, its 120 gain or nothing
Sculptor in LHaRGB from a bortle 6 during the new moon period.
L ~ 10hrs
RGB ~ 3hrs each
Ha ~ 2hrs