Fotodiox’s Aputure V-Control is a new affordable follow focus unit that uses Canon’s USB protocol to electronically drive focus and control other common controls on Canon DSLRs.
The Aputure V-Control works in both photo and video mode. It provides remote control for switching between still and video modes, as well as adjusting aperture, shutter speed, ISO and exposure compensation. The kit includes dual and single 15mm rail mounts for mounting to your HDSLR rig via the 1/4-20 thread on the bottom of the unit.
The Fotodiox Aputure V-Control retails for $180 and is available here on Amazon.com.