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Measure Optical Cannot Be Zero — Must Be Film Plane to Tilt Axis Distance

CONFIRMED ALL RIGS

Summary

In Flair camera/lens setup, the Measure Optical value (also referred to as "Optical Offset") cannot be left at 0.00. It must be set to the physical distance from the camera's film/sensor plane to the middle of the tilt axis. Setting it to zero causes incorrect kinematics — Flair cannot correctly calculate camera position for Cartesian moves or target tracking. This is a fundamental camera measurement, not an optional field.

Symptoms

  • Camera/lens setup has Measure Optical set to 0.00
  • Cartesian moves don't go where expected
  • Target tracking behaves oddly — camera doesn't orbit correctly around the target
  • Periprobe / probe / snorkel setups may show this as an X (Front) Nodal Offset

What Measure Optical Is

Measure Optical = the distance from the camera's film/sensor plane (indicated by the Φ mark on the camera body) to the centre of the tilt axis of the robot.

This is a physical measurement you take with a tape measure. It is typically 3–10 cm for most lens/camera combinations. It is never zero because the camera body and lens always place the sensor some distance in front of the tilt axis.

For a standard lens: measure from the camera body's film plane marking to the tilt axis of the robot head.

For a probe/periprobe/snorkel lens: use the X (Front) Nodal Offset field with the distance from the sensor to the front optical element of the periscope, as per the Probe/Snorkel lens setup mode.

Fix

  1. Physically measure the distance from the camera film plane (Φ mark) to the tilt axis centre
  2. Enter that value in Setups → Camera/Lens Setup → Measure Optical
  3. Values are typically in the range 3 cm – 15 cm (0.030 m – 0.150 m) — never 0
  4. For periprobe setups: use the lens's Tilting Lens mode; set X (Front) Nodal Offset to the distance from sensor to lens front; all other values at 0 (per Timothy Heys Cerchio's advice)

For Laowa probe setups

Timothy Heys Cerchio: "Measure from Sensor to lens front and use that value as X (Front) Nodal Offset. All other values at 0"

confidence_score: 0.90

WhatsApp Excerpts

[18/3/2023, 7:46:23 am] ~ Chavez.Camera: Don't forget to add measure optical offset.

[Context from March 2023 thread — approx line 15084-15090]: "Measure optical...Can't be 0" — operator reminder during Periprobe setup discussion.

Official Documentation

Flair Classic Manual — Ch.5 Setups: Camera and Lens Setup

Flair 7 Manual — Ch.5 Setups: Camera Mount Setup