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Laowa Periprobe / Macro Lens Setup

Probe lenses place the optical viewing point far in front of the camera body. Flair must therefore be told the correct tube length/nodal offset so that target tracking and Cartesian movement are calculated around the lens, not around the camera mount. A singularity is a geometry where the required robot or focus solution becomes unstable or impossible.

[BOTH] Laowa tube lenses (Periprobe, Pro2be) and periscope lenses (35° and double 45°) can be configured in Flair for focus control and target tracking. The key difference from a standard lens is the nodal point geometry: the imaging plane is offset along the tube from the camera mount, and for angled periscopes, there is also a vertical offset.

Rig suitability

A long probe/macro lens changes the reach and load balance the rig needs to handle. A Cinebot Mini is not designed for use with a long probe lens or for tight macro shots — it can be used to demonstrate or test the calibration procedure itself, but a larger-reach rig is the appropriate platform for an actual probe/macro shoot.

Straight Tube Lenses (Periprobe / Pro2be)

Nodal point and measure offset

Do not use the lens's own focus markings — ignore them entirely. Flair calibrates the lens from physical measurements.

Measure offset: The distance is measured from either:

  • The flat surface on the front of the tube: use a measure offset of approximately +0.01 m
  • The back of the curved surface of the tube: use approximately -0.015 m

Plus: add the X Nodal Offset from the tilt axis to the centre of the tube.

"Ignore the lens markings. With the probe you measure from the flat surface on the front or from the back of the curved surface of the tube. Set the measure offset. It will be about +0.01 for the front and -0.015 for the back PLUS the X Nodal Offset from the tilt axis to the Centre of the Tube." — @gordon_admin

Lens Setup also has a Measure Point field and an offset-diagram button next to the offset fields:

  • Measure Point — leave at zero if you are measuring the offsets from the film plane (the convention used above for probe lenses); a non-zero value shifts the reference point forward of the film plane instead.
  • Offset diagram button — opens a diagram showing the offset directions for different camera-mount configurations (e.g. top mount). Use it to confirm which physical direction each offset field (X Nodal Offset, Measure Offset, any vertical offset) corresponds to for how the lens is actually mounted on your rig, rather than assuming the sign/direction.

Creating the lens entry and driving it during calibration

  1. In Flair's lens list, create a new lens entry, give it a descriptive name, and enter its focal length.
  2. Drive the lens to each calibration position as you go. A standard MRMC lens motor can usually be turned by hand for calibration, but some motors — for example a Tilta lens motor — cannot be back-driven by hand at all. For those, calibrate using the motor's wireless follow-focus controller (or by driving the axis from Flair), not by trying to turn the barrel manually.
  3. To hand control back to Flair after driving the lens with a wireless controller, disable the controller (for example, double-press its function button) so Flair can move the axis directly.

If the lens motor moves during calibration but the on-screen focus value doesn't change (or the axis doesn't respond as expected once tracking is engaged), the focus axis direction is probably inverted. Open Focus Axis Setup, toggle Reverse, apply, re-enable the axis, and re-run the calibration move from Flair — then re-check the Infinity point, since inverting the axis resets what "zero" means.

Three-point calibration procedure

  1. Infinity point: Zero the focus at the infinity mark or focus on something as far away as possible and mark the barrel at that position.
  2. Mid-range point: Place a target approximately 8–12 inches away, focus on it, and enter that distance as the second calibration point.
  3. Close focus point: Place a target approximately 1 inch away, focus on it, and set as the close mark.
  4. Extra points (optional): Flair allows adding further calibration rows beyond these three points — useful on probe/macro lenses where the focus response is non-linear near the close/macro end of the range. Add a row for each additional barrel marking, measure the actual distance for each mark, and store it, then run Calibrate → Complete Calibration → Apply → Save.

After these three points are set correctly, the lens should be able to target-track and work in "Follows Target" mode.

Focus calibration alone is not enough

Completing the point-by-point focus calibration only sets up correct focus distance at the rig's home orientation. You must also complete the nodal/measure offsets above — without them, a probe lens can focus correctly at zero pan/tilt but will not track a target correctly as the camera angle changes. See Target Tracking with Probe Lenses below for how to verify this.

Laowa Pro2be barrel marking offset

The focus notches on the Pro2be barrel are referenced from the front Nodal Point of the lens:

  • Close focus (0.004 m) and mid-range (0.15 m) are marked from the front of the lens, not from the camera mount.
  • These differences can be resolved with either Camera Mount offsets or Measure Offset in Lens Setup.

1:1 macro point singularity

At the 1:1 ratio focus distance, the target pushes behind the nodal point. The rig will want to flip 180° (or stretch the arm fully out) to compensate. Be aware of the 1:1 point on the lens and do not target-track through it.

35° Single Periscope Module

The 35° angled module is handled with the extra settings in Lens Setup:

  • Tube length — the length of the probe tube
  • Tilt angle — set to 35° for the single angled module

Flair Classic has supported these settings for some time; recent Flair 7 releases also support them.

Double 45° Periscope Module

The double 45° periscope bends twice, effectively pointing the optical axis back to horizontal. Flair treats this configuration as a shorter straight probe with an additional vertical offset:

  • Front (X) Nodal Offset: approximately 33 cm
  • Vertical (Z) Nodal Offset: approximately –30 cm (the second 45° mirror drops the optical axis below the camera axis)

"The double 45° module can be treated as a short(er) straight probe [33cm Front (X) Nodal Offset] with a Vertical (Z) Nodal Offset — typically around –30cm." — @gordon_admin

Target Tracking with Probe Lenses

Once correctly calibrated, probe lenses can use Flair's target tracking to maintain focus on a subject as the rig moves. The calibration must be accurate — errors in the measure offset or nodal offsets will cause the focus to drift off-target as the camera angle changes.

For precise calibration verification: programme a move that changes the camera angle substantially while tracking a fixed target, then check whether focus holds through the move.

A quicker practical check: set the lens's focus mode to Follows Target, switch the hand controller to Cartesian control, and orbit the rig around the tip of the lens while tracking a fixed target. If the nodal/measure offsets are correct, the target stays framed through the orbit; if the framing drifts or wanders, re-check the Measure Offset, Measure Point, and nodal offset values before re-testing.

YouTube 07 - Lens Calibration Part 2 Flair Classic

▶ 04:35 — Setting Measure Offset and Nodal Offset fields in Flair's lens setup — the same fields Laowa-specific values are entered into

YouTube Calibrating a Probe Lens Flair 7

▶ 00:43 — Creating the probe lens in Flair 7's lens setup ▶ 04:43 — Setting up the tube/nodal offsets ▶ 07:33 — Testing the calibration: Follows Target + Cartesian orbit around the lens tip

Source: Laowa Periprobe Setup — talk.mrmoco.com
Source: New Laowa 35° and double 45° periscope lenses — talk.mrmoco.com