man hours in developing it i say. the principles are there with the on screen touch focus. what i would like is to have a preset A and B position with timer then hit record and it will pull focus based on those inputs.

Birger Engineering has such a product already. http://www.birger.com

Does anybody know the protocol for 4/3 lenses (not m4/3, if there is any difference)?

Tapping the contacts from the 4/3-m4/3 adapter would be easy and controlling the high end Olympus lenses with some external device would be really cool.

@AndersM

would it be possible to make a usable follow focus using the internal motors of the lenses?

With Wi-Fi cameras it can be simpler.

@Vitaliy_Kiselev is right, it's already almost possible using Wifi control with the GH3 (and it should be the same for the GF6 and G6), and doing some dev/scripting using what is described in this topic : http://www.personal-view.com/talks/discussion/6703/control-your-gh3-from-a-web-browser-now-with-video-/p1) :

The good things :

• with the wifi focus control, you have 4 commands : wide fast / wide slow / tele fast / tele slow
• with the wifi focus control, you have 256 values from minimum to infinity
• each time you call one of these functions, the GH3 returns the value of the actual focus state (from 0 to 255)
• you could use the "touch to focus" or the manual focus functions to memorize the focus points you're interested in, and then use them in your script

The complexity :

• the speed depends on the lens used. So you basically have to handle every lens model when you code the focus application
• the network / processing delay when executing a focus command can become too long when trying to smoothly rack focus. ie during my tests with the 20mm 1.7 if you use "fast wide / fast tele" there is some hiccups between each occurrence of the command, if you use "slow wide / slow tele" there is no hiccups, but it's really too slow (because you are limited by the number of command the GH3 can process in a second, max is around 10/s). With other lens, I'm pretty sure you can fine tune and have a decent wifi follow focus program.