Canon EF vs. Canon RF
Comparing 2 standards across 9 specifications. 8 key differences identified.
The Canon EF Mount (introduced in 1987 for the EOS autofocus SLR system) revolutionized photographic camera design as the first 100% all-electronic lens mount, eliminating all mechanical aperture linkages and autofocus drive shafts. Featuring a 44.0 mm Flange Focal Distance and a large 54.0 mm throat diameter, over 150 million EF lenses were manufactured over 33 years.
The Canon RF Mount (introduced in 2018 for the EOS R system) is a 3-tab full-frame mirrorless bayonet mount featuring a 20.0 mm Flange Focal Distance, a wide 54.0 mm inner throat diameter, and an advanced 12-pin high-speed data bus. Retaining the large 54mm diameter of the classical EF mount, it enables ultra-fast aperture lenses such as the RF 28-70mm f/2L and 50mm f/1.2L.
Specification Comparison Table
9 Parameters| Parameter / Spec | ||
|---|---|---|
|
Flange Focal Distance (FFD)
|
44.00 mm (1.732 in) | 20.00 mm (0.787 in) |
|
Inner Throat Diameter
|
54.00 mm (2.126 in) | 54.00 mm (2.126 in — identical to legacy Canon EF mount) |
|
Bayonet Tabs
|
3 locking tabs with clockwise twist | 3 asymmetrical stainless steel bayonet tabs with clockwise mounting twist |
|
Electronic Interface
|
8 gold-plated electronic contacts (expanded to 11 pins on EF super-telephoto lenses for teleconverters) | 12 contact pins (high-bandwidth bidirectional bus for lens control ring and Coordinated IS up to 8 stops) |
|
Camera Systems
|
Canon EOS-1D X Mark III, EOS 5D Mark IV, EOS 6D II, EOS Rebel series, Cinema EOS C300/C500 | Canon EOS R5 / R6 / R3 / R8 / R, Cinema EOS C70 / C80 / C400, APS-C EOS R7 / R10 |
|
Internal Actuators
|
Internal USM (Ultrasonic Motor) in lens body + internal electromagnetic aperture diaphragm (EMD) | — |
|
Variants
|
EF (Full Frame), EF-S (APS-C with rubber bumper back-focus extension), EF-M (discontinued APS-C mirrorless) | — |
|
Legacy Adaptability
|
— | 100% native AF/IS compatibility with all Canon EF/EF-S lenses via Canon EF-EOS R adapter (24mm spacer) |
|
Lens Control Ring
|
— | Physical programmable control ring on all native RF lenses (aperture, ISO, exposure compensation) |