I have been aggravated by (and bellyaching about) the ridiculous lack of a way to control the focusing motors in these lenses directly when shooting video, using a follow-focus wheel.
Video shooters are still strapping janky gear-tooth strips onto these lenses, and then bolting bulky mechanical follow-focus mechanisms on the OUTSIDE of lenses that have focusing motors already built in.
I can only imagine that manufacturers refuse to make direct control available in order to protect their "cinema" lens lines, where a manual normal lens sells for thousands of dollars. And yet they sell some falsely-named "hybrid" lenses that are supposedly somehow better for video... despite lacking even geared focusing rings that are compatible with follow-focus units... let alone a control port that could be used for a focusing wheel to use the autofocus motors.
I looked at the Canon camera-control SDK, and sure enough... focus control is omitted from their entire line, except for two PTZ cameras that aren't suitable for cine use.
A side project I've been neglecting is controlling autofocus on Sony Alpha cameras (specifically the A7ii and A7iii which I have) for the purpose of focus-stacking: shooting a few dozen shots with minimal-step focal differences and blending them all in photoshop later.
It took me a while to find the API; Sony made one then pretty much scrubbed it from the internet and has ignored my emails asking for one :-)
But even with the API, achieving results are tricky. Whether or not the focus motor steps properly seems to be based on how busy the camera is at the time... I'm trying various combinations of [shoot] - [sleep] - [step the focus] - [sleep] - [shoot] but the exactly which of these steps actually succeeds just seems so damn random.
BlackMagic does some pretty innovative stuff. They offered an Arduino add-on board that could communicate with and control their cameras over SDI, including access to the Canon EF mount and its commands.
Somebody did in fact create a control board with a knob to control lens focus through this thing. It can be done. The manufacturers just refuse to do it.
I have been aggravated by (and bellyaching about) the ridiculous lack of a way to control the focusing motors in these lenses directly when shooting video, using a follow-focus wheel.
Video shooters are still strapping janky gear-tooth strips onto these lenses, and then bolting bulky mechanical follow-focus mechanisms on the OUTSIDE of lenses that have focusing motors already built in.
I can only imagine that manufacturers refuse to make direct control available in order to protect their "cinema" lens lines, where a manual normal lens sells for thousands of dollars. And yet they sell some falsely-named "hybrid" lenses that are supposedly somehow better for video... despite lacking even geared focusing rings that are compatible with follow-focus units... let alone a control port that could be used for a focusing wheel to use the autofocus motors.
I looked at the Canon camera-control SDK, and sure enough... focus control is omitted from their entire line, except for two PTZ cameras that aren't suitable for cine use.