The utter joy of manual focus

[K12beano]

Well we have "AF Fine Tune" these days - I know it's not the same as adjusting for the focus plane, but it is one of those compromises that leaves the critical bit to the user and eases manufacturing tolerance problems. You used to hear all the time of lenses going back to the service people....

[Super Slo Mo]

Ah yes, this is true.

I'm not entirely sure how that works although have used it. I would assume it adds a correction factor to the required focal distance?

[K12beano]

I think - though I may have this completely wrong - that it's just "tinkering" in the software to effectively fool it into focusing the lens at a slightly different point to correct for the variation in actual lens to sensor distance.