This has had a small amount of screen stretch and has had no calibration or anything else done to it, on top of that its just a screen grab :)
In the image you can clearly see the outer shell showing in a single sub and the core is not blown out and full of detail, whilst M27 is quite a bright object a lot of what we image on a day to day basis are also pretty bright objects
This was done with a 16" F/6.8 scope on Pier-9, so I am hoping members may take on board that with some of our faster piers at F/2.8, F/3.3 & F/3.6 that collect 4/5x the amount of signal in the same time scale why we do not need long subs :)
Even a scope that is F/5 is more or less one F/stop faster, so will collect twice the amount of signal in the same 120 second period
Add to this
- the modern noise rejection algorithms & dithering, longer subs at times will actual decrease the quality of the data you will receive. Shorter subs are also less likely to be affected by outside forces like wind gusts, scudding clouds and short periods of bad seeing.
- Sky brightness- We are Bortle-2 so require far less integration time to reach a good SNR level before diminishing returns becomes an issue of course, than what is required for Bortle 5-9 skies or example. Smarter people than I will be able to do the maths on this I am sure :)
I will await the backlash and counter argument LOL
Steve - the antagonist of this particular story