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Canon EF lens mount
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Canon EF lens mount
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. The mount was first introduced in 1987.
Canon claims to have produced its 100-millionth EF-series interchangeable lens on April 22, 2014.
The EF mount replaces its predecessor, the FD mount. The standard autofocus lens mounting technology of the time used a motor in the camera body to drive the mechanics of the focus helicoid in the lens by using a transfer lever. The key innovation of the EF series was to use a motor inside the lens itself for focusing. This allowed for autofocusing lenses which did not require mechanical levers in the mount mechanism, only electrical contacts to supply power and instructions to the lens motor. The motors were designed for the particular lens they were installed in.
The EF mount reversed the mechanical logic of the FD mount. The FD mount provided the three-eared bayonet fitting on the camera body, and each FD lens provided a breech-lock receptacle to register and fasten the lens to the bayonet. The EF mount reverses this logic, providing the bayonet on each lens, and a receptacle on the camera body.
When the EF mount was introduced in 1987, it had the largest mount diameter (54 mm internal) among all 35 mm SLR cameras.
The EF series includes over eighty lenses, encompassing focal lengths from 8 to 1200 mm. Many EF lenses include such features as Canon's ultrasonic motor (USM) drive, an image stabilization system (IS), diffractive optics (DO) and, particularly for L-series lenses, fluorite and aspherical lens elements.
Its large diameter and relatively short flange focal distance of 44.0 mm allows mechanical adaptation of EF camera bodies to many types of non-EF lenses. It is possible to mount lenses using the Nikon F mount, Olympus OM, Leica R and universal M42 lens mounts (among others) by the use of a mechanical adapter without electronic control of the aperture or autofocus. In contrast, parfocal adaptation of EF lenses to non-EF camera bodies is not possible with only a mechanical adapter that does not contain optical elements.
EF mount lenses are somewhat compatible with newer Canon bodies, though the reverse is not true:
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Canon EF lens mount
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. The mount was first introduced in 1987.
Canon claims to have produced its 100-millionth EF-series interchangeable lens on April 22, 2014.
The EF mount replaces its predecessor, the FD mount. The standard autofocus lens mounting technology of the time used a motor in the camera body to drive the mechanics of the focus helicoid in the lens by using a transfer lever. The key innovation of the EF series was to use a motor inside the lens itself for focusing. This allowed for autofocusing lenses which did not require mechanical levers in the mount mechanism, only electrical contacts to supply power and instructions to the lens motor. The motors were designed for the particular lens they were installed in.
The EF mount reversed the mechanical logic of the FD mount. The FD mount provided the three-eared bayonet fitting on the camera body, and each FD lens provided a breech-lock receptacle to register and fasten the lens to the bayonet. The EF mount reverses this logic, providing the bayonet on each lens, and a receptacle on the camera body.
When the EF mount was introduced in 1987, it had the largest mount diameter (54 mm internal) among all 35 mm SLR cameras.
The EF series includes over eighty lenses, encompassing focal lengths from 8 to 1200 mm. Many EF lenses include such features as Canon's ultrasonic motor (USM) drive, an image stabilization system (IS), diffractive optics (DO) and, particularly for L-series lenses, fluorite and aspherical lens elements.
Its large diameter and relatively short flange focal distance of 44.0 mm allows mechanical adaptation of EF camera bodies to many types of non-EF lenses. It is possible to mount lenses using the Nikon F mount, Olympus OM, Leica R and universal M42 lens mounts (among others) by the use of a mechanical adapter without electronic control of the aperture or autofocus. In contrast, parfocal adaptation of EF lenses to non-EF camera bodies is not possible with only a mechanical adapter that does not contain optical elements.
EF mount lenses are somewhat compatible with newer Canon bodies, though the reverse is not true:
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