When I look at my subs they seem to lack sharpness, is there something I can do to improve this or I have I reached the limit of my equipment or seeing conditions?
I know that my C8 SCT isn’t a great choice for imaging, but it’s fine until I can afford something that’s going to be significantly better (I’m not sure what that something is yet, or how much better it could be). My usual FWHM focus values are around 4 +/- 0.1 using an ASI1600MM for the imaging camera, unbinned with a 0.63 reducer.
The mount and guiding setup seems good, typically total guiding RMS values are around 0.3 px using a ST80 with an ASI120MM. I built an Ardufocuser and control everything through NINA, including the autofocus, manual focusing doesn’t improve the focus and an out of focus collimation check looks fine.
I’ve attached a single auto-stretched sub as an example. And also the semi-finished image, I'm attempting to make best use of a Pixinsight trial.