To me the best method of focussing is in daylight to find infinity,choose a lens preferably a fixed focal and focus on infinity,then note the focus point on the distance scale,some use tape,but this is messy,I suggest, using a toothpick applying a small point of white paint on the barrel where the focussed point aligns with the distance line. This leaves a 1mm point that is neat and easily seen. Frigging around trying to focus is a pain and is time consuming (many exposures at 2-3 minutes) Zooms may need several tests because the infinity point can change with focal length.

PS. The moon is also a useful infinity check.

Dave's clichés

To me, the best method of focussing is in daylight to find infinity, choose a lens (preferably a fixed focal) and focus on infinity, then note the focus point on the distance scale. Some use tape, but this is messy. I suggest using a toothpick to apply a small point of white paint on the barrel where the focused point aligns with the distance line. This leaves a 1mm point that is neat and easily seen. Messing around trying to focus is a pain and is time-consuming (many exposures at 2-3 minutes). Zooms may need several tests because the infinity point can change with the focal length.

PS. The moon is also a useful infinity check.