With M42, I think the key to pulling out the Trapezium without blowing out the core and yet keeping decent nebulosity is to embrace as low an f/ratio as possible, use extreme short exposures and embrace longer integration times.
This example is at f/2 (Hyperstar using a ZWO ASI294mc), 2 second exposures x 153 = 306 seconds. I wanted to demonstrate what is possible on Hyperstar in five minutes, but over-ran by 3 frames. I have had to resize it from a full screen 32" 4K UHD 52Mb file to a mere 217kb to get it to fit into Cloudy Nights, so it has a lost a little. However, one can still see the four principle stars of the Trapezium (there are actually eight stars in that cluster, but splitting them to that level of detail is probably impossible).
At slower speeds, say, f/6.3 I suspect the trick then might be to use 4 second exposures over perhaps 10 minutes. However, most EAA people tend to go for longer (short) exposures (perhaps 15 to 20 seconds) and then shorter total integration time. I think this probably demonstrates some type of crossover point between EAA and AP. There is no escaping from a need to maximise the photons captured and total capture time is the crucial parameter. My experience is that better quality detail often tend to come from shortening exposures, but over a longer time, notably at f/2. Robin Glover (author of SharpCap) eloquently explains this far better than me on YouTube.
EDIT after reading post #17 to correct an omission. This too was low gain (100 in SharpCap).
Edited by Noah4x4, 26 January 2022 - 11:27 AM.
