The Newt mirror is spherical and produces spherical aberration but not too severe as you can see from the main Altair shot in 10s exp recording stars to mag12 and fainter. Some earlier mono shots with a aperture mask on a spike show sharper results here with an explanation as to why.
Results last night were curtailed when the battery died but the M57 shot [right] is a single frame as the stars traversed the field of the now static scope - quite pleasing to watch! An overhaul of drive with replacement batteries is in order for next try.
My video clip here