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Base curve radius (BCR) or simply base curve (BC) is the measure of an important parameter of a lens in optometry. On a spectacle lens , it is the flatter curvature of the front surface. On a contact lens it is the curvature of the back surface and is sometimes referred to as the back central optic radius ( BCOR ).
Canon in 2011 made the first fisheye zoom lens, both circular and rectangular. That lens was the Canon EF 8-15mm f/4L Fisheye USM. Canon in 2012 made the first wide angle lens with Image Stabilization. That lens was the Canon EF 24mm f/2.8 IS USM. Canon in 2013 created the first telephoto with built-in 1.4× extender.
The Canon TS-E 24 mm f / 3.5L II is a tilt-shift, wide-angle prime lens that provides the equivalent of the corresponding view camera front movements on Canon EOS camera bodies. Though it uses Canon's EF lens mount, it does not provide autofocus.
The Canon EF-M lens mount, introduced in 2012, is a derivative of the Canon EF lens mount designed for use with the Canon EOS M mirrorless interchangeable-lens camera. The EF-M lens mount is one of Canon's two systems for mirrorless cameras, the other being the RF mount .
Canon full-frame cameras have used the EF lens mount since 1987. In comparison with that mount, the RF mount's inner diameter is the same at 54 mm. [1] The RF mount's flange focal distance at 20 mm is much shorter than that of the Canon EF and EF-S mounts at 44 mm.
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The Canon TS-E 90 mm f/2.8 is a tilt-shift, telephoto prime lens that provides the equivalent of the corresponding view camera front movements on Canon EOS camera bodies. Unlike most other EF-mount lenses, it does not provide autofocus .
Canon New FD lens mounting surface.. The FD lens mount is a breech-lock mount, which is a variation of the common triple-flanged bayonet attachment. The advantage of the breech-lock over the bayonet is that neither the contact surfaces between the body and lens, nor the signalling mechanisms, rotate against each other when the lens is mounted.