The EF lens mount is the standard lens mount on the Canon EOS family of SLR film and digital cameras. EF stands for "Electro-Focus": automatic focusing on EF lenses is handled by a dedicated electric motor built into the lens. Mechanically, it is a bayonet-style mount, and all communication between camera and lens takes place through electrical contacts; there are no mechanical levers or plungers.
In 2003, Canon introduced the EF-S lens mount, a ...
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The EF lens mount is the standard lens mount on the Canon EOS family of SLR film and digital cameras. EF stands for "Electro-Focus": automatic focusing on EF lenses is handled by a dedicated electric motor built into the lens. Mechanically, it is a bayonet-style mount, and all communication between camera and lens takes place through electrical contacts; there are no mechanical levers or plungers.
In 2003, Canon introduced the EF-S lens mount, a derivative of the EF mount that is strictly for digital EOS cameras with a 1.6x crop released after 2003. EF lenses can be mounted on EF-S bodies, albeit with cropped image, while EF-S lenses cannot be mounted on EF bodies.
The EF mount replaces its breech-lock predecessor, the FD mount. The proximate cause for its introduction was the advent of autofocus, and the key innovation was placing the focusing motor in the lens, rather than in the body, requiring no mechanical linkages between the lens and the body, only electrical ones.
When the EF...
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