Canon EOS AF Lens Control
 

Hi,

I'm trying to reverse-engineer the EOS-AF protocol, to ultimately build an (open source) adaptor that would allow remote-controlling focus and aperture, while keeping information about zooms from the camera (since the 500d has a bug where it unlocks video settings when zooming, reverting to auto mode).

Apertus has some code that seems to send control information to the lens, but it is not really documented.
But, since they have it, they must have reverse-engineered it, or found some documentation about the protocol...

(My own attempts, using an arduino to wiretap the communication failed, since the MCU is too slow for a Canon-lens, but Tamron-lenses are OK, since they talk 5x slower... but still not enough...)


So, could anyone point me to the old thread where you discussed this at length (search found nothing though) or give some information about a source for documentation?