This is a simple 3D printed mount and sketch to turn a traditional follow focus into an input device.  The original purpose was, well, pulling focus (in a CG shot), but the combination of high resolution, stable output, and marking disc make it useful for other applications.

Parts List

Follow Focus: (Cheap, as FFs go, and nice because you can dial in some resistance.)

Set screws (Optional. The hard stops annoyed me so I replaced them with M3 set screws.):

3D printed mount: or (Inventor Fusion file)

Teensy 2.0++: (You could surely use a simpler–and cheaper–board.  I just happened to have one around.)

Pinion (32T 32P.  A true 0.8 gear would be better but this worked):

Rotary Encoder:

Breadboard: (again, what I had lying around)



Arduino Sketch


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