Focus Drifts to Infinity When Switching from Pan/Tilt Tracking to Target Tracking¶
Target Tracking Ongoing All rigs BOTH
Summary¶
When switching the tracking mode mid-session from Pan/Tilt Tracking (PTR) to Target Tracking (On), the focus axis sometimes drifts to infinity — even when Focus Follows Target was working correctly before the switch. This is an intermittent bug reported across multiple rigs and Flair versions. No definitive root cause has been confirmed by MRMC; community workarounds reduce occurrence but do not eliminate it.
This issue should be treated as part of the wider focus-at-infinity + Carts / Target Tracking failure family. In some cases only focus drifts. In worse cases, the robot itself moves because the Cartesian solver is trying to correct an invalid focus/target reference.
Symptoms¶
- Tracking mode was Pan/Tilt Tracking (or any non-TT mode), then switched to Target Tracking: On
- Focus axis begins moving toward infinity (maximum distance) after the switch
- The rig continues to move — focus does not stop at a safe point
- Switching back to PTR or engaging E-stop halts the focus movement
- Issue is intermittent — some mode switches work correctly
- Reported across Bolt Jr+, Cinebot Max, and other rigs
- Seen in multiple Flair versions (7.x)
- Related reports mention Camera Orbital, Carts / Locked View, and target or focus distance showing infinity
Root Cause¶
Not fully confirmed. Most likely cause: when switching tracking modes, Flair re-initialises the focus axis reference. If the target distance at the moment of switching is computed as infinity (e.g. because the cart target is far away, or because focus is at its limit), the new FFT calculation attempts to drive focus to that reference.
The issue is closely related to the general "focus at infinity + carts" problem — see TT camera orbital drift carts.
The April 2024 runaway thread also reported that Carts Off stopped the movement and that infinite focus / orbital / carts mode were suspected together. The November 2024 drift thread independently narrowed the gentler variant to Camera Orbital + Cartesian mode + focus/target at infinity.
Workarounds¶
Before switching tracking modes¶
- Turn Carts Off before changing tracking mode.
- Before changing from PTR / Camera Orbital to Target Tracking, bring the focus axis to a realistic working distance (e.g. 100–500 cm).
- Confirm the focus readout shows a sensible distance.
- Then switch tracking mode.
Do not switch modes with Carts active on a live rig
If focus/target distance is invalid, the failure can escalate from focus drift to unexpected robot motion. Keep crew clear and the E-stop reachable when changing Target Tracking modes.
Check cart target distance¶
If the cart target is very far from the rig when you switch modes, the focus reference will be computed from that large distance. Position the cart target close to a realistic subject distance before switching.
After switching — verify focus before running¶
After switching to Target Tracking:
- Check the focus axis readout before running the move.
- If it shows infinity or a very large distance, do not run — address the focus position first.
- Move focus manually to a working distance, then store the waypoints again.
- If the rig starts moving, hit E-stop or Carts Off immediately, then save the job for support.
Report to MRMC¶
If the issue occurs consistently on your system, submit a bug report to MRMC including:
- Flair version
- Rig type
- Tracking mode sequence (what you were doing before the switch)
- Focus axis readout at time of switch
WhatsApp Excerpts¶
"Every time we switch from pan tilt tracking to target tracking, focus drifts to infinity." — Multiple operators (reported across various segments, 2023–2025)
"Intermittent — some mode switches work correctly, others trigger the drift. No repeatable set of steps that always reproduces it." — Community consensus
"It happened while the set was live. E-stop was required. Spacebar didn't stop it in time." — Operator (paraphrased)
"Usually orbital, Cartesians and as Ben said focus at infinity." — Niko (2024-11-07)
"Started to move slowly. Turned carts off. Set focus closer. Back to cartesians and no need to power cycle or restart." — Niko (2024-12-07)
Related Issues¶
- See also: Camera Orbital + Carts Mode Causes Rig to Drift (Target at Infinity) — Camera Orbital + Carts drift (same root mechanism: focus at infinity)
- See also: FFT Focus Stuck at Maximum Distance — Must Set Focus Before Engaging Cart Control — FFT focus locked at infinity after cart control engagement
- See also: Bolt Runs Unexpectedly in Carts After Switching from Camera Orbital — E-Stop Required — Bolt running unexpectedly after tracking mode switch
- See also: Focus At Infinity - Cartesian / Target Drift and Unexpected Gotos — Wider focus-at-infinity Cartesian drift guidance
Related Tutorials¶
▶ 00:00 — Overview of Focus Follows Target mode, prerequisites, and common setup mistakes
Revision History¶
| Date | Change | Editor |
|---|---|---|
| 2026-05-24 | Initial extraction | Tom D / Claude Code |