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.
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.