thanks Meru/Alpal
Focus was confirmed with a Bahtinov mask at the beginning of each imaging session and locked in place, however i guess focus must have shifted slightly as the ambient temps dropped. Collimation could also be a factor, as I only have a laser collimation thingy - not the full suite of newtonian collimation tools. Seeing was pretty variable over both imaging sessions for that image - great until about midnight when it hit 100% RH, and then a light fog as the temp dropped from there.
FWIW I also have a 200mm f4 imaging newtonian that i've been working with over the last few months, so i've been able to learn and practice much of the capture and processing workflow (have uploaded some of those shots to my astrobin page). PixInsight and now this second longer focal length scope are just the latest AP toys
Would love a permanent obs, but I still need to convince my better half
