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Laowa Periprobe / Probe Lens — Barrel Rotation Conflicts With Focus Motor

EXPERIMENTAL ALL RIGS

Summary

The Laowa Periprobe (Laowa 24mm T14 2× Periprobe or similar) has a 90° mirror objective at the tip. The main lens barrel can rotate to orient the image. However, the focus gear ring and the barrel rotation ring are mechanically linked — rotating the barrel also turns the focus gear. This makes it impossible to use a focus motor AND rotate the barrel simultaneously. The image also reverses horizontally when rotated beyond a certain point. This is a lens design limitation with no complete fix; workarounds involve locking the barrel and using Flair axis assignments that don't rely on focus motor + barrel simultaneously.

Symptoms

  • When you twist the lens barrel (tube) around with the image-orientation 'pan' ring, the focus gear ring turns too
  • Running the focus motor simultaneously with barrel rotation is impossible — they physically interfere
  • Image appears reversed (mirrored) left-to-right depending on barrel orientation
  • Camera may appear upside-down with certain barrel orientations
  • Play in the focus locking ring even when locked

Design Limitation

The Periprobe barrel is mechanically integrated with the focus ring. There is no way to separately rotate the image orientation without also turning the focus gear on the same lens body. This is a vendor design issue.

David Goldsmith suggested treating the tip centre as the nodal point and rotating around it for clean orbital moves.

Workarounds

[EXPERIMENTAL] Lock the barrel and don't use focus motor during barrel rotation

  1. Lock the barrel in a fixed orientation (e.g. image upright) before rigging to the robot
  2. Set up lens calibration with the barrel locked in this fixed position
  3. Do not attempt to rotate the barrel during a live move
  4. For focus pulls: use the MRMC focus motor normally with the barrel locked

[EXPERIMENTAL] Mount vertically, use 6th axis for tilt instead of barrel rotation

If orbital rotation is required: 1. Mount the lens vertically and let the robot arm handle the angle 2. Use a 6th axis (roll or tilt) to orient the shot rather than rotating the barrel

[EXPERIMENTAL] Accept the coupling and work around it in post

If only minor barrel rotation is needed between setups (not during a move): - Disengage the focus motor first - Rotate the barrel manually to the desired orientation - Re-engage and recalibrate focus

Contact Laowa

Simon Wakley noted: "Probably not worth the bother" as a design issue. If this is a recurring requirement, contact Laowa (kevin@venuslens.net) about whether future hardware revisions address the coupling.

confidence_score: 0.78

WhatsApp Excerpts

[18/3/2023, 7:23:28 am] ~ Steven Moses: Any help with kinematic setup, camera and lens setup for Laowa Periprobe with 90 degree objective?

[18/3/2023, 7:39:16 am] David Goldsmith: Top mount, treat the centre of the lens at the centre of the tube as the nodal point (can't recall if this acts as a perfect nodal point but it's nice to rotate cleanly around)

[Earlier context from the chat - approx Oct 2022, lines 5475-5490]: "when you twist the lens barrel (tube) around with the 'pan' ring the Focus gear turns around too...Impossible to use both at the same time" "image is reverse Right"; "camera upside down too"; "play even when the locking ring is clicked into place"

Official Documentation

Flair Classic Manual — Ch.5 Setups: Probe/Snorkel Lens Setup