Building a low-cost remote follow focus system using radio-controlled servo components

2007Forum Follow Focus

19 Jahre alt. Geräte und Preise können sich seitdem geändert haben.

UmstrittenDie Beteiligten waren sich nicht einig. Lies die Befunde als Positionen, nicht als Antwort.

A functional follow focus system can be constructed for under $400 using a digital proportional radio transmitter, receiver, servo motor, and mounting bracket.
Standard RC servos have limited rotation ranges, typically 120 degrees or less, which restricts their ability to control focus across the full range of some camera lenses.
Larger gear ratios compensate for limited servo rotation but reduce precision and force delivery at the gear teeth.
RC servos operate as open-loop systems without feedback, unlike professional motor systems that use closed-loop control for improved accuracy.
Modifying RC servos by adjusting internal potentiometer resistors can extend their rotation range beyond the standard 120 degrees, though excessive modification can cause continuous motion.
Multi-turn motors with 5-7 turn capability provide better control range and power than standard RC servos but require different receiver compatibility.
RC servo-based follow focus systems work adequately for video lenses and low-budget productions but show precision limitations with stiff 35mm cinema lenses.
RC servos generate audible mechanical noise during operation.
A DIY system serves well as a backup to rented professional follow focus equipment.

The technology discussion spans from 2007, with servo specifications and available products likely changed significantly since then.
The rotation modification technique described is experimental and requires careful tuning to avoid causing malfunction.
Performance varies greatly depending on lens type and focus range requirements.
Compatibility between RC receivers and professional multi-turn motors was not conclusively resolved in the discussion.
One participant claimed modifications to extend servo rotation work well with video lenses up to 25mm but encounter problems with 50mm lenses.
The claim about Heden motor internals containing a Faulhaber motor is mentioned but not independently verified in the thread.