# What is lens metadata, which values do Cooke /i lenses and ARRI cameras give per frame, and should I rely on the 'focal length' value as a camera solve input?

- id: art_01M5MCHVQEY76C545JMBDV0QX4
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T12, T19 · tags: none
- updated: 2026-10-23T12:42:41.255Z
- url: https://veyrul.com/articles/art_01M5MCHVQEY76C545JMBDV0QX4

In the ARRI SDI Metadata white paper dated 25 July 2023, ALEXA 35 SUP 1.2 changes add Lens Effective Focal Length (LDI26) and Lens Entrance Pupil Position (LDI27) alongside the existing Lens Focal Length (LDI04, 1/1000 mm).

In the ARRI SDI Metadata white paper dated 25 July 2023, ALEXA 35 SUP 1.2 changes add Lens Effective Focal Length (LDI26) and Lens Entrance Pupil Position (LDI27) alongside the existing Lens Focal Length (LDI04, 1/1000 mm).

Curator qualifications: Rewrite 'ARRI's newest lens fields' as 'in the 2023-07-25 white paper, ALEXA 35 SUP 1.2 changes add ...' (C2-B85-AUDIT4 hint); newer ARRI documents not checked. That plain focal length is unsuitable for pinhole solves is the producer's inference (labelled synthesis), not an ARRI statement. Cooke /i Part I strand (S22) not reinspected; Cooke Part III withheld per producer hold.

Limitations: One white paper.

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

```json
{
  "citations": [
    {
      "url": "https://cookeoptics.cn/wp-content/uploads/2021/11/Cooke-i-Technology-Part-I-2021.pdf",
      "note": "ARRI SDI Metadata white paper, cover (Date: 25 July 2023), change table, LDI04, LDI26, LDI27 rows"
    },
    {
      "url": "https://www.arri.com/resource/blob/327826/a17ae3b8bf7e8d487d6d01648bdf432e/arri-cameras-sdi-metadata-white-paper-data.pdf",
      "note": "ARRI SDI Metadata white paper, cover (Date: 25 July 2023), change table, LDI04, LDI26, LDI27 rows"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] In the ARRI SDI Metadata white paper dated 25 July 2023, ALEXA 35 SUP 1.2 changes add Lens Effective Focal Length (LDI26) and Lens Entrance Pupil Position (LDI27) alongside the existing Lens Focal Length (LDI04, 1/1000 mm). · locator: ARRI SDI Metadata white paper, cover (Date: 25 July 2023), change table, LDI04, LDI26, LDI27 rows · source: https://cookeoptics.cn/wp-content/uploads/2021/11/Cooke-i-Technology-Part-I-2021.pdf

Rights:
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