[mnw21cam]

And you can do tricks such as lucky imaging or active optics (depending on your budget) to further improve the resulting resolution. Lucky imaging is tricky on something as dim as Andromeda, but has been shown to be just about possible.

[bhouston]

I haven't seen lucky imaging used on dim objects by anyone I know. I personally do not have a large enough aperture to collect enough light for that. But I've used it on bright planets before via AutoStakkert[1]: https://www.astrobin.com/full/06dzki/0/

[1] https://www.autostakkert.com

[mnw21cam]

Lucky imaging was always a tool for use on planets and the moon. Anything bright.

It's hard to do dim objects because there's less for the software to inspect in each frame to determine the luckiness and distortion, but you can maybe use fortuitous bright stars in the frame to index off. You also need to collect a huge number of images to get any sort of signal to noise ratio. This video is an example of the technique actually used on a dim object, though the results were fairly modest because of murky British skies.

https://www.youtube.com/watch?v=5s9xbZ5G-wk