I may have a little electronics project coming up for which I'll need to control something like a focus servo of the type often used with radio remote focus gear.
I am aware that there are two generations of this stuff, the earlier analog approach which is functionally equivalent to a PWM driven radio control servo (from which the technology arose), and the more modern approach with digital communications, about which I know next to nothing. Various manufacturers' servos and radio receivers are advertised as being cross-compatible, so there's presumably some sort of de-facto standard at play.
As with many de-facto standards in niche industries, googling doesn't turn up any documentation. I have been informally advised that the older PWM types operate on exactly the same protocol as a common radio control servo, that is, 1-2ms duty cycle PWM at about 50Hz, but that's hardly concrete intel and I'm not sure what the situation is with the more modern ones at all.
Can anyone point me in the direction of some paperwork on this stuff?