I just imagined that they were manual focus lenses Simon
I use my Leica lenses on my Sony cameras and focus at the taking aperture
Makes no difference to the EVF.
I use shutter priority for sports shots with the manually set aperture and it compensates with the ISO
It's a better solution than when I use a lens like the Canon 70-200 because the camera recognises the lens and ,if I'm on shutter priority ,it will open the lens rather than increase the ISO
Obviously it can't do that with a manual lens and as they have bags of ISO headroom an increase in the ISO is the preferred option
Focus shift is never a problem