Had a go at this one last year with a C14 at native 3900mm, and although the galaxy turned out OK, the coma from just off centre to the edges was horrible.
Just had another go over the past couple of nights (only 2hrs total in 15min subs - luminance only), but with the addition of a friends Starizona corrector.
What a difference...
The stars are still not perfect, but a whole lot better than last time (I still need to optimize the spacing), and its now working at a more reasonable 2700mm FL.
Sampling is still only at about 0.42"/pixel with the QHY9 (c.f 0.28"/pixel last time). The first night was very good with FWHM'S coming in at 1.58" in the 15min subs; the second night only gave about 2.1" stars.
I didn't take flats, so its just a synthetic FF and I just cropped the full frame to hide some of the corner vignetting (full frame is reduced in size by about 30% to fit the file size limit).
Needs a lot more exposure, (still very noisy) but looking promising so far..
I have also attached a 100% crop of the centre of the frame showing the galaxy - North down & East to the right.
