Best exposure and total integration times

Yep, that's about right.  I'm shooting 90 seconds with Ha filters, 60 seconds for unfiltered exposures with the 1600mm.  My 2600MC exposures were around 60 seconds also if I recall.

I think that's what I'm using, gain 0.

Yes, that is correct and often desirable. But at f/2 you might want to trade read noise for higher well depth so you can expose longer. This would mean you can reduce the amount of subs. Maybe not as much a concern with the IMX533 but with larger sensors it‘s quite time consuming to stack 800 or more subs.

I think you are in the ballpark.  I am not sure if gain 100 is unity for your camera, but it makes sense to get to the firmware sweet spot depending on the target you are shooting.  But I think there is value in using other settings depending on the target, etc.  As Torben stated, there may be objects with a very high dynamic range that could blow out and thereby be unmanageable during processing.  Just because gain 100 gets you back to full dynamic range, it does not necessarily (I didn't look up your camera graphs) mean that you are going to get full well depth at that location.  Gain zero usually offers max dynamic range and pixel well depth.  But for two of my cameras, both dramatically lose full well depth regardless of whether the firmware gives you full dynamic range.  Either way, it might be worth trying different settings in situations that might seem where it might make sense, like super bright details that otherwise max out under very short exposure times.  In general, even the gain zero settings need not require super long sub lengths.  I generally stick close to recommendations from the Sharpcap exposures.

I have to say that with the RASAs, it is amazing how well they can capture the delicate wisps of the IFN using near unity gain and the type of exposures that you are using.  In comparison longer scopes that show the same images require such long exposures!

Alan

Thanks guys these are really helpful comments. So what’s your view on total integration time with a RASA 8? Even a conservative estimate puts the RASA at 4-5 times the light gathering. So if 2hrs of RASA is equivalent to 8 hours plus at F6, I had assumed that 2 hrs was more than plenty.
Max

With my RASA 11, I have gotten good results with 3 hrs or more, depending on the subject.  In some cases, less.  The caveat from my opinion is that I have not had that much time with my 11, since I live in a weather restricted location.  And my processing has changed over time.  However, the real test for me is that I have gone back to subjects that I did two years ago and find that with proper sub exposure and gain settings (I do believe that you can use a single setting for most all subjects and do just fine, but that making adjustments based on subject can improve things) it is remarkable what you can do with relatively short total integration times.  I suggest that you do the experiment yourself.  Easy to do.  Next time you image, take subs on a single subject over the whole night, say 6-7 hours.  You can then integrate full time, and a couple less times, say down to 2 hrs., even 1 hr, using a properly chosen subset of subs for each integration time.  Compare what you get.  Then decide for yourself how you want to spend your time…  And that may change as you get more discriminating of your own images and compare to like images from others using the same gear.  The going conventional wisdom is that more subs are better.  Well, that is true.  1,000 will be better than 10.  However, the useful question takes into account the fact that the improvement with more subs results in diminishing returns per an asymptotic approach to some ideal.  Collect the subs you need to meet your standard.  I have seen those who publish RASA images that use integration times that meet or exceed what others here publish using long fl  telescopes.  But I would ask, why did you buy a RASA?  Its almost like there are some awards for total integration time bragging rights!  RASAs take the "macho" out of imaging!  But most importantly, for us weather and location restricted imagers, it allows us to do this hobby where it otherwise would be very impractical.

Alan