The TB3 won't work with the Fz for a few reasons:
- The connectors are wired for the spectrum
- The power output isn't quite right. The spectrum can drive the Fz fast and slow and tailors its power so it won't overheat the motors. Since the TB3 can't scale its power output in the same way as the spectrum ST4, we would have to turn up the current output very high to get the torque we need and that uses too much battery and gets motor too hot!
There are a couple good articles that we have written to show off the spectrum's ST4's advanced electronics that talk about this too!
Is there a motorized focus on the market for the TB3?
There are a couple that historically work well for timelapse - http://store.berkeysystem.com/focus-motor/ is a good one that you can adapt. Brian Berkey is a good guy too!