Canon EF 24mm f/1.4L USM

Buy it from:

Professional wide-angle lens with an ultra-large maximum aperture of f/1.4. This is the first EF lens to employ both a replicated Aspherical lens element to suppress distortion and spherical aberration, and a UD lens element to correct lateral chromatic aberration. Thanks to the floating construction, excellent corner-to-corner delineation is attained from 10 in. (25 cm) to infinity.

That f/1.4 is not a typo--this is the fastest ultra-wide-angle lens in the world. The first EF lens to combine Aspherical and UD Ultra-low Dispersion glass L-series optical technologies, the 24mm f/1.4L provides outstanding sharpness and contrast even wide open. It focuses down to 10 inches/0.25m, and the AF is what you'd expect from a professional Canon lens with USM—fast and silent, with smooth full-time manual focus available at any time.