[DiscoDuck (Paul)]

Originally Posted by dpastern

Yeah, Jon [Rista] over at CN has argued pretty much the same - keep subs short, and lots of them, and don't go ballistic with the bias/offset. I personally think you're bias/offset settings are too high and you would do better to drop them.

Thanks. May be the case. Still experimenting as just got the camera last month.

Originally Posted by peter_4059

Does well depth change with gain or does increasing gain just increase the rate that you fill the well?

Well depth will stay the same, but the counter will overflow sooner with increasing gain! i.e. at the gain I was using, I think it is about 0.5 e per 16 bit chunk of ADU, so 32 ADU per electron. Hence only 2048 electrons can be counted before it saturates, even though I think the wells are 20000 electrons or so.

Originally Posted by peter_4059

What bias/offset settings are you using?

I was, for that, using gain 202 and offset I think 50. The higher gain was to get a lower read noise.

Originally Posted by dpastern

I haven't bought my ZWO 1600 - yet. I'm gonna start with 100/21 and see how things go when I do get it. A friend on YouTube shoots @ 139/21 from memory and gets great results too. From my understanding, you get no real gain from bumping up the gain (no pun intended!) - it's far better to preserve SNR.

Yeah. I think as long as you're sky limited then unity gain (139) is fine. But at unity gain narrowband subs need to be quite long to be sky limited. Even at the gain I was using, I think it would be something like 14 minutes. I was only shooting 10 min subs.

For normal luminance on the other hand, at gain 139 I get sky limited subs in under 60 seconds.