A quick video showing the responsiveness and speed of the Okii USB follow focus. Just watch the focus distance window on the top of the lens. Camera in use is a 60D with an EFS 17-55mm f/2.8 lens.
Focus step size: medium
Focus command send rate: 15 commands per second
Please note that I start recording right at the beginning, as you can see the LED change to red and the counter on the camera's top LCD begin blinking. This demonstrates focus control is still active while recording.