What the thread found

• The RED camera has a P-tap connection on its battery holder that can theoretically power follow focus controllers, but its reliability is inconsistent.
• Using the P-tap to power RED accessories has been reported to cause unexpected camera shutdowns or failure to power on in some cases.
• Powering follow focus equipment directly from the RED camera body through the accessory plugs is not recommended because the camera cannot reliably handle power draws from non-RED peripherals.
• A separate cable with an AB connector can be sourced to power follow focus units independently rather than relying on camera connections.
• When using P-tap breakout boxes, reversed polarity connections can trigger thermal fuses that protect the camera, causing temporary shutdowns that resolve after a few minutes.
• Mounting follow focus equipment on the camera support sled with independent power is a more stable alternative to powering from the RED itself.

Depends on

• The discussion concerns RED camera hardware from around 2008, which may not reflect current camera designs.
• No consensus was reached on the best solution; some users reported success with P-tap powering while others experienced consistent problems.
• The reliability issue with P-tap powering was not fully explained or resolved.
• Different follow focus models and control boxes may have different power requirements and compatibility.

Gear in this thread

MDR

Parts

Follow Focus

Same gear or parts

1. 2026Power loss on Trinity 2 / Artemis 2 with large cameras (A35, Venice): causes and battery solutions.DisputedFacebookArri Artemis Trinity
2. 2026Pulling focus and zoom yourself while operating, especially on live showsOperator practice
3. 2026Swapping an ARRI ALEXA 35 between tripod/studio and Steadicam® mounting: baseplate choice and fastest workflow.FacebookSteadicam operators group
4. 2025Custom servo zoom controller for Tilta Nucleus system using Bebob Zoe housing and 7-pin LEMO connectorFacebookSteadicam operators group