Great image-very well done,a useful educational image-great to see,It would be good see more astro images along these lines that people can enjoy and find useful.
Hi Elio, Thanks.
I used a crappy lens – 17-200mm, and what I didn’t notice is that when it is used in a vertical position with each shot the zoom ring moved slightly, so by the time I collected 30 images the difference between the first and the last was more than I’d say 15%.
PixInsight could hardly work this out, but because the centre of the frame look OK I didn’t worry about the corners.
Also, thanks for pointing out the 9th Messier …