> a focus change should really be intentional; auto focus isn't that. Might depend on what you're filming though.

As a solo operator, autofocus is great. Maybe the right metric is the number of crew per camera. 2-3 crew per camera? Manual focus is fine. 2-3 cameras per crew member, like solo filming a podcast or a theatre show? I'd choose autofocus every time.

Well.. The automatic part comes from the camera directing the settings mostly. The lens would be motorized focus/aperture.

For motion picture cinematography, I've seen remote controlled focus anyway. I don't see why you could not have a good motor built I to the lens and remote control it. If the external motor focus is quick and precise enough, then the internal motors should be as well.

If you're just filming a/your talking head autofocus with face recognition is very reliably and helps when people unintentionally go out of focus ;)