What the thread found

• Some Zeiss lenses can exhibit binding or resistance at certain focus distances, particularly in near focus ranges, which may cause attached follow focus gears to disengage.
• The weight and pressure of a matte box or heavy filter setup can deform the front housing of a lens slightly, causing uneven resistance in the focus ring that may lead to gear slippage.
• Zeiss lens gear rings have small set screws that connect the focus gear to the worm drive, and if one loosens, it can travel into a tooth gap and cause gear engagement problems.
• Follow focus systems do not require calibration across the entire lens throw and can be calibrated to a shorter working range like 2 feet or closer to avoid problem areas.
• Manual rotation of the focus ring can reveal lens binding issues that might not be apparent when using a motorized follow focus.
• Some follow focus motors are available with wider gear options that allow extended travel range and may help avoid engagement loss at specific distances.
• Using support structure from matte box rods rather than camera body dovetails can reduce vibration-induced motor drift during use.

Depends on

• The specific lens model and motor system were not fully detailed in the discussion.
• No definitive diagnosis was reached before the shoot concluded.
• The heavy filter load may have masked or contributed to the underlying cause in ways that would not reproduce on other jobs.
• The observation was limited to one particular camera and lens combination on one production day.

Parts

Follow Focus

Same gear or parts

1. 2026Swapping an ARRI ALEXA 35 between tripod/studio and Steadicam® mounting: baseplate choice and fastest workflow.FacebookSteadicam operators group
2. 2026Pulling focus and zoom yourself while operating, especially on live showsOperator practice
3. 2025LC-1 (Lens Control-1) follow focus system: wired architecture, motors, and early operational experience (1990s).FacebookThe Steadicam Group
4. 2024Modifications to a Steadicam Scout rig for expanded power distribution and connectivityGeneral Discussion