What the thread found

• Focus motor twitches during operation can be caused by RF interference from wireless transmitters or radio communication equipment
• Changing the wireless frequency channel may resolve twitching issues, though the problem can recur at different locations due to varying RF environments
• Motor cables can act as antennas and conduct RF interference into receiver circuitry; isolating motor cables from other cables may reduce twitching
• A partially broken receiver antenna with damaged threads can cause focus motor control issues
• Receiver software updates provided by the manufacturer may resolve intermittent twitching and dropout problems
• RF interference is particularly pronounced in enclosed spaces like sound stages where radio signals bounce off walls and insulation
• Battery voltage up to 18 volts does not cause motor twitching problems in the BFD system

Depends on

• The exact cause of twitching was difficult to reproduce and test during normal operation
• The problem appeared inconsistently across different filming locations and jobs
• Multiple potential causes were identified but not all were conclusively tested by the original reporter
• One user mentioned a broken antenna as their cause but acknowledged it may not apply to all cases

Gear in this thread

Moduluscatalog, BFD

Parts

Follow Focus

Same gear or parts

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4. 2025LC-1 (Lens Control-1) follow focus system: wired architecture, motors, and early operational experience (1990s).FacebookThe Steadicam Group