This electronic focus controller allows accurate and repeatable focus on EF lenses mounted to any DSMC2 camera body by giving the user direct control of the lens's internal focus motor, remapping it to a full turn of the large, ergonomically designed hand wheel. Also controls Iris, run/stop, and other functions with several assignable buttons.

From the Manufacturer:
Reliably adjust your lenses off-camera with the Teradek RT Smartknob Wired Smart Controller. Use the included cable to connect the Smartknob to an MK3.1 receiver or Latitude lens controller and actuate focus or iris motors, or EF lens focus or iris. The advantage to an off-camera system is the ability to place it wherever you want to improve ergonomics. Use the 1/4"-20 mounting threads to attach it to a clamp or articulating arm, keeping it close at hand whenever an adjustment is necessary. Around the exterior of the unit are 6 customizable buttons which can change the function of the unit, start/stop recording, and more. The included marking disk is backlit for easy readability in low-light environments.