Canon · Mirrorless mount
Canon RF — flange distance, protocol, and adapter compatibility
Canon's full-frame mirrorless mount. Same 54 mm throat as EF but 20 mm flange (vs EF's 44 mm) and a 12-pin contact array supporting faster lens-to-body bandwidth. Mechanical-only EF→RF adapters are 24 mm thick, preserving every EF and EF-S lens's autofocus, IS, and aperture control with no glass.
Mount specifications
- Flange focal distance
- 20 mm
- Throat diameter
- 54 mm
- Electronic protocol
- Canon RF
- Supported formats
- full-frame, APS-C
- Manufacturer
- Canon
- Introduced
- 2018
- Status
- Active production
Canon RF on the flange-distance axis
Canon RF sits at 20 mm — highlighted in orange below. The flange-distance gap between the mirrorless and SLR clusters is the room a mechanical adapter occupies; that gap is why almost every SLR lens adapts onto every mirrorless body, and why the reverse is mechanically impossible.
Adapting Canon RF lenses onto other bodies
You own Canon RF glass and want to mount it on a body with a different lens mount. Rows are sorted by feasibility.
| Body mount | Result | Adapter examples | Caveats | ||||
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Body mount Canon RF (cine) | Native |
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Body mount Canon EF-M | Mechanical |
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Body mount Nikon Z | Mechanical |
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Body mount Sony E (incl. FE) | Mechanical |
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Body mount Fujifilm X | Mechanical |
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Body mount C-mount | Mechanical |
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Body mount Fujifilm GFX (G-mount) | Speed booster |
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| Speed Booster equivalence calculator Plug in any Canon RF lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Fujifilm GFX (G-mount) (medium-format), plus the full-frame equivalent angle of view after the body's crop stacks on top.
50.0 mm × 0.71 on the reducer. 0.99 stops brighter than f/1.80. 35.5 mm × 0.79× (medium-format sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = | |||
Body mount Micro Four Thirds | Speed booster |
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| Speed Booster equivalence calculator Plug in any Canon RF lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Micro Four Thirds (MFT), plus the full-frame equivalent angle of view after the body's crop stacks on top.
50.0 mm × 0.71 on the reducer. 0.99 stops brighter than f/1.80. 35.5 mm × 2× (MFT sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = | |||
Body mount L-Mount | Speed booster |
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| Speed Booster equivalence calculator Plug in any Canon RF lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a L-Mount (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
50.0 mm × 0.71 on the reducer. 0.99 stops brighter than f/1.80. 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = | |||
Body mount Leica M | Speed booster |
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| Speed Booster equivalence calculator Plug in any Canon RF lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Leica M (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
50.0 mm × 0.71 on the reducer. 0.99 stops brighter than f/1.80. 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = | |||
Adapting other lenses onto a Canon RF body
You own a Canon RF body and want to mount glass from other systems. Mirrorless-lens-onto-DSLR-body combinations are omitted (rear element collides with the mirror box).
| Lens mount | Result | Adapter examples | Caveats |
|---|---|---|---|
Lens mount Canon RF (cine) | Native |
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Lens mount Canon EF | Mechanical |
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Lens mount Canon EF-S | Mechanical |
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Lens mount Canon FD | Mechanical |
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Lens mount Nikon F | Mechanical |
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Lens mount Sony A / Minolta A | Mechanical |
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Lens mount Fujifilm GFX (G-mount) | Mechanical |
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Lens mount M42 (Pentax / Praktica screw mount) | Mechanical |
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Lens mount Leica M | Mechanical |
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Lens mount Pentax K | Mechanical |
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Lens mount PL (Positive Lock) | Mechanical |
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Lens mount Canon EF (cine) | Mechanical |
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Lens mount Exakta | Mechanical |
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Lens mount T-mount (T2) | Mechanical |
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Lens mount Praktica B | Mechanical |
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Lens mount Konica AR | Mechanical |
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Lens mount Minolta SR / MC / MD | Mechanical |
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Lens mount Olympus OM | Mechanical |
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Lens mount Contax/Yashica (C/Y) | Mechanical |
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Lens mount Canon EF-M | Speed booster |
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Lens mount Nikon Z | Speed booster |
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Lens mount Sony E (incl. FE) | Speed booster |
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Lens mount Fujifilm X | Speed booster |
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Lens mount Micro Four Thirds | Speed booster |
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Lens mount L-Mount | Speed booster |
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Lens mount C-mount | Speed booster |
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Adapter SKU teardown
Curated adapter SKUs that involve the Canon RF mount on either side, with the operational specifics — body-side electronic contact count, firmware-update path, weather sealing, and whether optical glass is in the path.
Canon EF-EOS R
released 2018Canon EF lens → Canon RF body
- 12 body-side contacts
- no firmware updates
- weather sealed
- no glass — pass-through
- Canon-first-party adapter for EF / EF-S → RF / RF-S bodies. Preserves AF, IS, electronic aperture on every EF lens since 1987.
- Three variants: plain, Control Ring (extra rotation ring), Drop-In Filter (variable ND or circular polarizer slides in).
Viltrox EF-EOS R5 (autofocus EF-to-RF)
released 2024Canon EF lens → Canon RF body
- 12 body-side contacts
- firmware updatable
- not weather sealed
- no glass — pass-through
- Third-party alternative to Canon's official EF-EOS R; significantly cheaper, similar AF behaviour on most EF lenses.
- Firmware-updatable via USB-C, which is uncommon for the price point.
Firmware history
- v1.00
- Initial release covering R5 / R6 / R6 Mark II + curated Canon EF lens list
- v1.10
- Refined AF performance with EF 70-200 f/2.8L IS III / EF 100-400 f/4.5-5.6L IS II
- EOS R3 / R5 specific tuning
Approximate milestones — verify against the Viltrox firmware page for the authoritative changelog.
K&F Concept M42-EOS R Pro
released 2020M42 (Pentax / Praktica screw mount) lens → Canon RF body
- no firmware updates
- not weather sealed
- no glass — pass-through
- Pro-line M42 screw-mount onto Canon RF — Canon's 20 mm flange (vs Canon EF's 44 mm) leaves plenty of clearance for the adapter's body, and infinity calibrates cleanly on every R-line body (R5 / R6 / R6 II / R3 / R8 / R10 / R50 / R100).
- Mechanical-only — no electronics, no AF. Aperture is controlled by the M42 lens's own ring or stop-down lever. RF body's focus magnification and peaking aids handle manual focus.
Novoflex EOSR/LEM
released 2019Leica M lens → Canon RF body
- no firmware updates
- not weather sealed
- no glass — pass-through
- CNC-machined-in-Germany aluminum body, dual-screw bayonet retention, per-unit infinity-focus calibration with paper spec sheet. Leica M-mount glass (Leica, Voigtländer VM, Zeiss ZM, Konica M-Hexanon, 7Artisans) onto Canon RF bodies (R5 II / R5 / R6 II / R3 / R8 / R10).
- Mechanical-only — no AF, no electronic communication. Manual focus only with the RF body's focus peaking and magnify aids. The 20 mm RF flange + 27.8 mm M-mount flange leaves the adapter as a short, rigid ring (~8 mm thick).
- Lifetime warranty against manufacturing defects; the most expensive M → RF adapter on the market (~3-5× K&F / Urth equivalents).
Commlite CM-EF-EOS R
released 2019Canon EF lens → Canon RF body
- 12 body-side contacts
- firmware updatable
- not weather sealed
- no glass — pass-through
- Third-party EF → Canon RF adapter at ~50% the price of Canon's first-party EF-EOS R. Preserves AF / IS / electronic aperture on every EF / EF-S Canon and Sigma DG / Tamron Di USM / STM lens; USB-C firmware updatable.
- Functionally similar to Viltrox EF-EOS R5; Viltrox tracks slightly better on EF L super-telephotos in side-by-side tests, Commlite costs slightly less. Both lack the weather sealing of Canon's official adapter.
Firmware history
- v1.0
- Initial release — Canon EF / EF-S onto Canon RF (R / RP / R5 / R6) with AF / IS / electronic aperture
- v2.0
- R5 II / R6 II / R7 / R10 / R8 PDAF rule alignment
- EF-S APS-C crop-mode handling refinements
Approximate milestones — verify against the Commlite firmware page for the authoritative changelog.
Fotodiox FD-RF
released 2019Canon FD lens → Canon RF body
- no firmware updates
- not weather sealed
- no glass — pass-through
- Canon FD / FL breech-lock and New FD (FDn) bayonet lenses onto Canon RF bodies. Mechanical-only — Canon abandoned FD in 1987 and never made a first-party FD→RF adapter, so a third-party ring (Fotodiox / Urth / K&F) is the only path. No AF, no electronics.
- Built-in aperture actuator: FD lenses sit wide open off-camera, so the adapter holds the stop-down lever and the lens's own aperture ring then controls the diaphragm. The 42 mm FD flange clears RF's 20 mm by 22 mm — glassless, infinity preserved.
References
Common questions
- Can I use Canon EF lenses on an RF body?
- Yes — the Canon EF-EOS R adapter is a pure mechanical spacer (24 mm thick, no glass) that bridges EF's 44 mm flange to RF's 20 mm flange while passing the 8-pin EF protocol through to RF's 12-pin connector. AF, IS, and electronic aperture work on every EF and EF-S lens since 1987 across every RF body (R5, R6, R3, R7, R8, R10).
- Why does Canon RF use a 12-pin connector instead of EF's 8-pin?
- The four extra pins carry higher-bandwidth lens-to-body communication, used for in-lens metadata pass-through, the new RF Control Ring, and Dual Pixel CMOS AF II's per-frame focus telemetry. EF lenses still autofocus on RF through the adapter because the adapter exposes only the 8 EF-protocol pins to the lens — the RF body falls back to the EF subset automatically.
- Is there a Canon RF-to-Sony-E adapter?
- No usable one — Canon RF's electronic protocol is proprietary and undocumented, so no third party has produced a smart RF-to-E adapter with AF. Mechanical-only RF-to-E adapters exist (Fotodiox, Urth) but they break AF, IS, and aperture control. The standard cross-system path for Canon glass onto Sony E remains EF lens → Sony E body via the Sigma MC-11 or Metabones, not RF.