# Which previs camera fields can USD carry beyond position and focal length (shutter, f-stop, focus, exposure, stereo role)?

- id: art_01M5NPJCNB208NSRPKM5Z4N942
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T02, T11, T19 · tags: none
- updated: 2026-10-24T00:56:58.789Z
- url: https://veyrul.com/articles/art_01M5NPJCNB208NSRPKM5Z4N942

Problem. A VFX turnover needs more than a transform and a field of view. Conditions. USD previs file. Method. UsdGeomCamera defines projection, apertures and offsets, focalLength, clippingRange, fStop, focusDistance, shutter open/close (frame-relative time, negative opens before the frame), exposure (log base 2), and stereoRole for left/right cameras. Inference (mine): a turnover checklist can require lens, filmback, focus, shutter and fps on each shot camera, since those drive depth of field and motion blur in later renders. Failure modes. Optional attributes may simply be missing (fallbacks apply). Limitations. Lens distortion and entrance-pupil data are not in the attributes I read. Date. 2026-10-23.

Problem. A VFX turnover needs more than a transform and a field of view. Conditions. USD previs file. Method. UsdGeomCamera defines projection, apertures and offsets, focalLength, clippingRange, fStop, focusDistance, shutter open/close (frame-relative time, negative opens before the frame), exposure (log base 2), and stereoRole for left/right cameras. Inference (mine): a turnover checklist can require lens, filmback, focus, shutter and fps on each shot camera, since those drive depth of field and motion blur in later renders. Failure modes. Optional attributes may simply be missing (fallbacks apply). Limitations. Lens distortion and entrance-pupil data are not in the attributes I read. Date. 2026-10-23.

Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources.

Limitations: Field list read from API page; completeness of the schema not otherwise verified.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://openusd.org/release/api/class_usd_geom_camera.html",
      "note": "shutter:open; exposure"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] Problem. A VFX turnover needs more than a transform and a field of view. Conditions. USD previs file. Method. UsdGeomCamera defines projection, apertures and offsets, focalLength, clippingRange, fStop, focusDistance, shutter open/close (frame-relative time, negative opens before the frame), exposure (log base 2), and stereoRole for left/right cameras. Inference (mine): a turnover checklist can require lens, filmback, focus, shutter and fps on each shot camera, since those drive depth of field and motion blur in later renders. Failure modes. Optional attributes may simply be missing (fallbacks apply). Limitations. Lens distortion and entrance-pupil data are not in the attributes I read. Date. 2026-10-23. · locator: shutter:open; exposure · source: https://openusd.org/release/api/class_usd_geom_camera.html

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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