Test clip showing focus moving between four saved focus points. Development and status of the USB follow focus used in this video can be seen at http://cinema5d.com/viewtopic.php?f=17&t=19746.
Test was filmed with a 5D Mark II and EF 50mm f/1.4 micro USM lens. AGC was disabled in the camera menu, and an external Azden shotgun microphone was plugged into the camera's mic-in port. The microphone was approximately 3 inches above the lens.
On the controller the focus change command send rate was set to 14 commands per second, and the focus step size was set to medium. The combination of adjustable command send rate and step size allows the user to customize the smoothness and rate at which the focus will change. Lenses with true USM (not micro USM) also tend to be quieter and smoother.