@Vitaliy_Kiselev - I bet it would be a good solution, especially with wider lenses.
On the crane you can try this:
http://www.personal-view.com/talks/discussion/3363/electric-follow-focus#Item_3
really no competition to proper system, but on crane it could work for some shots.
@Vitaliy_Kiselev - Yup. Even the expensive ones are pretty noisy. Most of my stuff is dual system sound or mos, so it's a bit less of a concern.
As I remember all of cheap wired and wireless FF are noisy, some are noisy as hell. And are not really best.
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