Vive trackers don’t come with any zoom encoders or even an interface for connecting one, so how would you track zoom with it? You would need a totally separate lens encoding solution like Indiemark to get the zoom position. 

I've seen people (Matt Workman from cinematography database) actually attach a vive tracker to a traditional follow focus.

If you get the vive's rotation values in aximmetry, then you can create your own compound to map them to focus values.

Smart, but very DIY, though.

On a side note, if you're really into DIY, you can build a focus encoder for around $50 with off-the-shelf components (and a 3D printer for the case).

I made a prototype with a tiny ardunio board (a seeduino XIAO that costs around $6) and a regular 600PPR rotary encoder ($25 on Amazon). By loading a ready-made library for quadrature encoded signals, you actually get a precision of 600x4=2400 pulse per rotation. That's a native precision of 0.15° on the shaft, but if you take into account that your encoder gear will probably have a 1/4 or less of the teeth of your lense gear, that's actually around 2400x4= 9600 pulses or more per rotation of your lense (or 0.037° of precision).

With an OSC library you can send the data to aximmetry, and do your things there.

@ericmarodon: That Vive hack isn’t nearly accurate enough to be used for zoom tracking.