"An ultra-large-diameter single-focus lens that achieves the highest quality images available in its class. Equipped with 10-blade diaphragm and maximum aperture of f/1.2, this lens provides smooth, near circular bokeh. Perfect for those seeking to have a better control of depth of field and shooting at extreme low-light condition. Air Sphere Coating (ASC) in RF50mm f/1.2L USM optics greatly reduces the flare and ghosting issues. RF50mm f/1.2L USM features an additional control ring on the barrel that could be customised to control exposure settings; shutter speed, aperture, ISO and exposure compensation, effectively providing better control especially while shooting through the Electronic View Finder. The control ring has a tactile, easily distinguished surface and features a clicking mechanism that provides tangible feedback during adjustment. Filter Size: 77mm Max aperture: f/1.2 Additional Control Ring With ring USM motor Dust and Drip Resistant "