1June, 934, Canon, then also called Seiki Optical Research Institute, introduced the first experimental product "Kwanon" camera, which is an imitation of Leica, not a SLR. Canon's first SLR camera (with pentaprism viewfinder and reflective curtain) was launched by Canonflex in May. 1959. "Canonflex" has adopted many new technologies, such as interchangeable pentaprism viewfinder, automatic aperture, external selenium photocell exposure meter and so on. In addition, in the bright lens with the focal length range of R lens from 35mm to 135mm, a fully automatic aperture mechanism called "SUPER-ANOMATIC" is equipped. This linkage with the aperture mechanism of the fuselage is an important system connecting the fuselage and the lens group, which will gradually develop into FL lens and FD lens. In addition, the lens bayonet is changed from screw type to fastening method named back lock ring. Because there is no direct friction between the fuselage and the lens bayonet when the back locking ring is used, the wear phenomenon of the lens bayonet can be avoided. Finally, in optics, the accuracy of the lens is improved. R lens has released about 16 kinds of lenses, such as anti-telephoto wide-angle lens "R35mm f/2.5", highlight lens "R58 mm f/10.2" and telephoto lens "R1000 mm f//kloc-0"

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