# M42 — Camera mount flange focal distance and adapter feasibility

For M42, flange focal distance (mm) is 45.46 mm; mount type is SLR; format is 24X36 mm, verified against its source on 2026-08-13.

- **Mount name:** M42 _(verified: appears in the quote below)_
- **Flange focal distance (mm):** 45.46 mm _(verified: appears in the quote below)_
- **Mount type:** SLR _(verified: appears in the quote below)_
- **Format:** 24X36 mm _(verified: appears in the quote below)_

## What the source says

> M42 | 45.46 mm | SLR | 24X36 mm

## Sources disagree

More than one authority states this, and they do not state the same
thing. Both are reproduced with the source each came from.

### Flange focal distance (mm)

briansmith.com says flange focal distance (mm) is **45.46 mm**, as of 2026-08-13.

> M42 | 45.46 mm | SLR | 24X36 mm

Source: https://briansmith.com/flange-focal-distance-guide/

allphotolenses.com says flange focal distance (mm) is **45.5**, as of 2026-08-13.

> m42 | 45.5 | SLR 35mm camera

Source: https://allphotolenses.com/articles/item/c_6.html


### Mount type

briansmith.com says mount type is **SLR**, as of 2026-08-13.

> M42 | 45.46 mm | SLR | 24X36 mm

Source: https://briansmith.com/flange-focal-distance-guide/

allphotolenses.com says mount type is **SLR 35mm camera**, as of 2026-08-13.

> m42 | 45.5 | SLR 35mm camera

Source: https://allphotolenses.com/articles/item/c_6.html


## Source

- https://briansmith.com/flange-focal-distance-guide/
- https://allphotolenses.com/articles/item/c_6.html

Last verified: 2026-08-13. Review by: 2028-08-12.
Part of [Camera mount flange focal distance and adapter feasibility](https://referencesource.org/camera-lens-body-adapter-compatibility/).