On film, ver i and ii are sharp at f4.5, f8 gives you the depth of field to forget about focussing, just set it at 1.5m.
On digital they are both sharper across the field at f8, but usable at f4.5. Unfortunately I only found them good for digital black and white because of the terrible Italian Flag colour shifts.
Ver iii is amazing, my copy is sharp right into the corners at f4.5, slightly better at f8 but you really have to look for it. No colour shift on digital. I have used mine on Leica M240, Sl, SL2-S, Sigma Fp, Sony A7rii and A7s and it's wonderful on all of them.