# YS mount — Camera mount flange focal distance and adapter feasibility

For YS mount, flange focal distance (mm) is 55.00; mount type is SLR; format is 24×36 mm; production years is –1969, verified against its source on 2026-08-13.

- **Mount name:** YS mount _(verified: appears in the quote below)_
- **Flange focal distance (mm):** 55.00 _(verified: appears in the quote below)_
- **Mount type:** SLR _(verified: appears in the quote below)_
- **Format:** 24×36 mm _(verified: appears in the quote below)_
- **Production years:** –1969 _(verified: appears in the quote below)_

## What the source says

> YS mount | 55.00 mm | SLR | 24×36 mm | –1969 | | | | | Sigma, Upsilon, Accura, Polaris, Sun, Aetna, Beroflex, Petri, Raynox, N.P.S., Formula, Dionar, Universal, Soligor, Yashica, Spiratone. M42×0.75 (not to be confused with M42×1) Same as T-mount but with aperture coupling |

## 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)

en.wikipedia.org says flange focal distance (mm) is **55.00**, as of 2026-08-13.

> YS mount | 55.00 mm | SLR | 24×36 mm | –1969 | | | | | Sigma, Upsilon, Accura, Polaris, Sun, Aetna, Beroflex, Petri, Raynox, N.P.S., Formula, Dionar, Universal, Soligor, Yashica, Spiratone. M42×0.75 (not to be confused with M42×1) Same as T-mount but with aperture coupling |

Source: https://en.wikipedia.org/wiki/Flange_focal_distance

briansmith.com says flange focal distance (mm) is **55.00 mm**, as of 2026-08-13.

> YS mount | 55.00 mm | SLR | 24X36 mm

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


### Format

en.wikipedia.org says format is **24×36 mm**, as of 2026-08-13.

> YS mount | 55.00 mm | SLR | 24×36 mm | –1969 | | | | | Sigma, Upsilon, Accura, Polaris, Sun, Aetna, Beroflex, Petri, Raynox, N.P.S., Formula, Dionar, Universal, Soligor, Yashica, Spiratone. M42×0.75 (not to be confused with M42×1) Same as T-mount but with aperture coupling |

Source: https://en.wikipedia.org/wiki/Flange_focal_distance

briansmith.com says format is **24X36 mm**, as of 2026-08-13.

> YS mount | 55.00 mm | SLR | 24X36 mm

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


## Source

- https://en.wikipedia.org/wiki/Flange_focal_distance
- https://briansmith.com/flange-focal-distance-guide/

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/).