Canon RF mount: 20 mm flange focal distance, 54 mm diameter — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/canon-rf-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.
- RF replaced EF on Canon's mirrorless bodies: the 54 mm diameter stayed, and the flange distance went from 44 mm to 20 mm, which is why an EF-to-RF adapter is 24 mm thick.
- 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  Canon (lens mount guide)
throat / inner diameter  54 mm (mount diameter)  Canon U.S.A. press release, 2018
coupling  bayonet  —

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Canon: Camera lens mount guide (RF: 20 mm flange distance) — web — Publisher's page; dimensions are facts — https://en.canon-me.com/get-inspired/tips-and-techniques/choosing-right-lens-mount/
- Canon U.S.A.: Canon introduces four RF mount lenses (press release, 5 Sep 2018): RF mount 54 mm diameter — web — Publisher's page; dimensions are facts — https://www.usa.canon.com/newsroom/2018/20180905-rf
- 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=canon-rf-mount