Canon"s new fast aperture prime lens: the EF 24mm f/1.4L II USM. Replacing the EF 24mm f/1.4L USM, the EF 24mm f/1.4L II USM has been completely redesigned to provide an exacting partner lens to Canon"s new EOS digital SLRs, the EOS 50D and EOS 5D Mark II. Featuring a 13-element, 10-group lens, the EF 24mm f/1.4L II USM is designed to achieve the highest standards of image quality. Two high-precision GMo aspheric lenses are employed to correct various forms of aberration such as curvature of field and distortion, with a floating mechanism ensuring crisp corner-to-corner detail throughout the focal range. In addition, two UD lenses reduce the chromatic aberration common in wide-angle lenses. A fast, ultra-large maximum aperture of f/1.4 delivers excellent low-light performance, with the circular aperture offering the potential for creative out-of-focus highlights. A focal length of 24mm and a USM focus motor providing full-time manual focus also make the EF 24mm f/1.4L II USM ideal for situations where a wide-angle, high-performance lens is required. It features a fronth thread to accept 77mm optional filters.