L-Mount: 20 mm flange focal distance, 51.6 mm diameter — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/l-mount/  (sheet CC BY 4.0)
Basis: Published numbers only (sources per row); no bayonet geometry is published, so no file
Catalog version: 2026-10-20

Sizes: see table below
- Flange focal distance is the distance from the mount's reference face to the image plane; adapters and extension tubes must add exactly the difference between two mounts' flange distances to keep infinity focus.
- Shared by the L-Mount Alliance makers; full-frame and APS-C lenses use the same mount.
- No file: the bayonet's lug widths, angles, depths and locking geometry are not published by the maker, so nothing is drawn. Only the published numbers are given.

parameter  value  from
flange focal distance  20 mm  L-Mount Alliance
throat / inner diameter  51.6 mm (diameter)  L-Mount Alliance
coupling  bayonet  —

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- L-Mount Alliance: L-Mount overview (51.6 mm diameter, 20 mm flange distance) — web — Publisher's page; dimensions are facts — https://l-mount.com/en/Overview
- Wikipedia: Flange focal distance (table of mounts) — web — CC BY-SA 4.0 (text); dimensions are facts — https://en.wikipedia.org/wiki/Flange_focal_distance

No true-size file yet: the published figures do not fix the whole shape; a measured scan is planned.
API: https://xemstudio.com/api/geometry?object=l-mount