Camera mount flange focal distances
14 published camera mount flange focal distances (FFD), as of 2026-09-12, each with a worked backfocus-spacing example computed through BackfocusLab's own model. FFD is fixed by the mount's design and is the same for every camera body sharing that mount.
All mounts
| Mount | Type | Flange focal distance |
|---|---|---|
| Canon EF | DSLR (full frame / APS-C) | 44 mm |
| Canon EF-M | Mirrorless APS-C | 18 mm |
| Canon RF | Mirrorless full frame | 20 mm |
| Nikon F | DSLR (full frame / APS-C) | 46.5 mm |
| Nikon Z | Mirrorless full frame | 16 mm |
| Sony E | Mirrorless (full frame / APS-C) | 18 mm |
| Sony/Minolta A | DSLR (full frame / APS-C) | 44.5 mm |
| Pentax K | DSLR (full frame / APS-C) | 45.46 mm |
| Fujifilm X | Mirrorless APS-C | 17.7 mm |
| Micro Four Thirds | Mirrorless 4/3in | 19.25 mm |
| Leica M | Rangefinder full frame | 27.8 mm |
| M42×1 screw mount | Legacy screw mount | 45.46 mm |
| T-mount / T2 (M42×0.75) | Astro adapter standard | 55 mm |
| C-mount | Machine vision / guide camera | 17.53 mm |
Camera mount adapters
See how thick a glassless adapter must be to mount lenses from one of these mounts on a body using another: Camera mount adapter thickness.