# How do depth-of-field and hyperfocal-distance calculators differ in their assumptions (circle of confusion, hyperfocal definition), and what does ZEISS say?

- id: art_01M5ME5Z3X6WR7WZ9CEXZ97KS1
- 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, T19 · tags: none
- updated: 2026-10-23T13:11:08.663Z
- url: https://veyrul.com/articles/art_01M5ME5Z3X6WR7WZ9CEXZ97KS1

ZEISS uses z = D/1500 (0.029 mm for 24x36) in its charts, gives hyperfocal approximately f'^2/(z'k) and treats the circle of confusion as a format property; a secondary source records a second hyperfocal definition differing by one focal length (H = f^2/(Nc) + f) and calls the 'Zeiss formula' D/1730 apocryphal. CoC choice and the +f term shift results: for 50 mm at f/2.8 on full frame, 35.8 m (0.025 mm, +f), 31.0 m (ZEISS D/1500) and 29.8 m (0.03 mm, +f), recomputed by the curator.

ZEISS uses z = D/1500 (0.029 mm for 24x36) in its charts, gives hyperfocal approximately f'^2/(z'k) and treats the circle of confusion as a format property; a secondary source records a second hyperfocal definition differing by one focal length (H = f^2/(Nc) + f) and calls the 'Zeiss formula' D/1730 apocryphal. CoC choice and the +f term shift results: for 50 mm at f/2.8 on full frame, 35.8 m (0.025 mm, +f), 31.0 m (ZEISS D/1500) and 29.8 m (0.03 mm, +f), recomputed by the curator.

Curator qualifications: Documents and code read 2026-10-22; arithmetic only; no lens or light file tested. Wikipedia is secondary; calculator implementations not inspected.

Limitations: Documents and code read 2026-10-22; arithmetic only; no lens or light file tested.

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

```json
{
  "citations": [
    {
      "url": "https://lenspire.zeiss.com/photo/app/uploads/2022/02/technical-article-depth-of-field-and-bokeh.pdf",
      "note": "ZEISS (Nasse, 2010) Depth of field and bokeh PDF; Wikipedia Hyperfocal distance, oldid 1356333224 (raw); Wikipedia Zeiss formula, oldid 1308361662 (raw); curator recomputation, 50 mm f/2.8 on 36x24 mm"
    },
    {
      "url": "https://en.wikipedia.org/w/index.php?title=Hyperfocal_distance&oldid=1356333224",
      "note": "ZEISS (Nasse, 2010) Depth of field and bokeh PDF; Wikipedia Hyperfocal distance, oldid 1356333224 (raw); Wikipedia Zeiss formula, oldid 1308361662 (raw); curator recomputation, 50 mm f/2.8 on 36x24 mm"
    },
    {
      "url": "https://en.wikipedia.org/w/index.php?title=Zeiss_formula&oldid=1308361662",
      "note": "ZEISS (Nasse, 2010) Depth of field and bokeh PDF; Wikipedia Hyperfocal distance, oldid 1356333224 (raw); Wikipedia Zeiss formula, oldid 1308361662 (raw); curator recomputation, 50 mm f/2.8 on 36x24 mm"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] ZEISS uses z = D/1500 (0.029 mm for 24x36) in its charts, gives hyperfocal approximately f'^2/(z'k) and treats the circle of confusion as a format property; a secondary source records a second hyperfocal definition differing by one focal length (H = f^2/(Nc) + f) and calls the 'Zeiss formula' D/1730 apocryphal. CoC choice and the +f term shift results: for 50 mm at f/2.8 on full frame, 35.8 m (0.025 mm, +f), 31.0 m (ZEISS D/1500) and 29.8 m (0.03 mm, +f), recomputed by the curator. · locator: ZEISS (Nasse, 2010) Depth of field and bokeh PDF; Wikipedia Hyperfocal distance, oldid 1356333224 (raw); Wikipedia Zeiss formula, oldid 1308361662 (raw); curator recomputation, 50 mm f/2.8 on 36x24 mm · source: https://lenspire.zeiss.com/photo/app/uploads/2022/02/technical-article-depth-of-field-and-bokeh.pdf

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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