# item.guide
Side-by-Side Comparison Lens Mounts

Canon EF vs. Fujifilm X-Mount

Comparing 2 standards across 9 specifications. 9 key differences identified.

Comparing:
Canon EF
Fujifilm X-Mount

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.

View full Canon EF spec sheet →

The Fujifilm X-Mount (introduced in 2012 for the X-Pro1) is a dedicated APS-C mirrorless bayonet mount featuring a 17.7 mm Flange Focal Distance, a 40.7 mm throat diameter, and a 10-pin electronic interface. Designed exclusively for APS-C image circles, it allows compact lens designs optimized for Fujifilm's proprietary X-Trans CMOS sensors.

View full Fujifilm X-Mount spec sheet →

Specification Comparison Table

9 Parameters
Parameter / Spec
Flange Focal Distance (FFD)
44.00 mm (1.732 in) 17.70 mm (0.697 in)
Inner Throat Diameter
54.00 mm (2.126 in) 40.70 mm (1.602 in)
Bayonet Tabs
3 locking tabs with clockwise twist 3 locking tabs with counter-clockwise mount twist
Electronic Interface
8 gold-plated electronic contacts (expanded to 11 pins on EF super-telephoto lenses for teleconverters) 10 contact pins (opened to third parties in 2020: Tamron, Sigma, Voigtländer, Viltrox)
Camera Systems
Canon EOS-1D X Mark III, EOS 5D Mark IV, EOS 6D II, EOS Rebel series, Cinema EOS C300/C500 Fujifilm X-T5, X-H2, X-H2S, X-T30 II, X-S20, X-Pro3, X-E4
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)
Back Focus Distance
Minimum rear optical element clearance of 7.5 mm from sensor
Physical Aperture Rings
Standard mechanical aperture rings with 1/3-stop clicks on XF lenses