On the other hand, I would suggest that we need to check out how things work. Modern AF-lenses are not built for manual focus, anyway.
Good point. Even if the best manual focus experience come with the helicoids in lenses designed exclusively for manual focusing, it might be that under the compromises of supporting both AF and MF, the best solution will be focus-by-wire, at least once it is responsive enough. For one thing, FBW allows options like different "gearing ratios" between focus movement and focus ring rotation:
- a high ratio for big, quick shifts in focus, requiring only about a half turn from minimum to infinity, and
- a lower ratio for small, slow, careful focus adjustments.
Some Olympus lenses try to do this, shifting gearing ratios depending on whether the focus ring is rotated quickly or slowly.
The helicoids in mechanically coupled manual focus systems on AF lenses generally have a rather high gearing ratio, favoring speed over accuracy, which is one reason that some photographers find them inferior to pure manual focus lenses for precise manual focusing.