Thanks for your reply.
I have no focuser so far but I am considering buying one in the future. I hear what you are saying regarding seeing conditions and altitude of the target. I was aware of the altitude influence but I have no practical experience on this so far. So good to hear your advice about the 40 degree rule of thumb.
I have seen the focus assistant in SharpCap but I have not tried it by myself so far.
location: 49,55N, 7,89E; mount: EXOS-2 PMC; telescope: Meade 10" ACF; guidescope: Orion 50mm, cameras: Sony Alpha 6000, ASI 120MC-S, laptop: Lenovo; OS: Windows 10 64bit, software: Cartes du Ciel, Sharpcap, Ascom platform, AstroTortilla,