I just swapped my Edge8 for a Skywatcher 190 mak-newt and am setting up the new scope for imaging.
I think my collimation is not perfect but fairly close.
I have only had a chance to do a few trial runs and I am a little concerned about something. On my Edge8 and in my AT115EDT refractor I could get FWHM values as low as 1.6 arc-sec on the best nights and usually in the 2.5 'ish range on good nights.
So far, I had 3 nights to try the mak-newt using the same camera (ASI071pro with a Astronomik UV/IR cut filter) and my FWHM values were between 3.4 to 3.6 arc-sec each time according to CCDI. These were taken form individual short 20 second subs at zero gain focused using a Bhat Mask. So I was not overexposing and should not have had any meaningful tracking errors. Now maybe I just had three different nights of poor seeing, but I was expecting lower values. In addition the stars, while round, seemed a bit bloated.
Dumb question...if I had overstretched the image would that make the FWHM values larger? Because I did stretch the subs a fair amount to make sure CCDI would detect the stars.
To any mak-newt users, what type of FWHM values do you see on good or average nights seeing wise?
Edited by John Miele, 23 September 2019 - 12:30 PM.