From the Manufacturer
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 USMfast and silent, with smooth full-time manual focus available at any time.
Wide and Fast
If you need an ultra-wide angle and a large aperture, one of the following lenses will fit the bill. Ultra-wide-angle lenses can capture scenes beyond your natural field of vision. The EF 15mm f/2.8 Fisheye, the widest of them all, has a 180° angle of view. For more normal-looking wide-angle shots, there are longer wide-angle lenses up to 35mm with the maximum aperture you need.
Product Description
CANON EF 24MM f/1.4 USM -- This professional wide-angle lens boasts an impressive 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 a floating construction, excellent corner-to-corner delineation is attained from 25 centimeters to infinity Max. diameter & length (mm) - 83.5 x 77.4 Weight - 550 grams