The Canon EF24mm f/1.4L II USM, an interchangeable L (luxury)-series lens for Canon EOS-series SLR cameras. The large-diameter, wide-angle lens boasts an ultra-wide maximum aperture of f/1.4, the brightest* in its class.
Incorporating special optic materials like glass mold aspherical lenses and UD (ultra-low dispersion) lenses, the new high-performance L-series EF24mm f/1.4L II USM realizes enhanced image quality over its predecessor, the large-diameter wide-angle EF24mm f/1.4L USM, which released to favorable reviews in December 1997.
In addition to two high-precision glass mold aspherical lenses that enhance overall image quality, the EF24mm f/1.4L II USM features two UD lenses that minimize color bleeding (chromatic aberration of magnification), which tends to occur on the periphery of photos taken by wide-angle lenses. Newly developed Subwavelength Structure Coating minimizes ghosting and flare caused by light with a large angle of incidence.
The new high-performance lens also incorporates a dust- and moisture-proof body that provides added protection in the harshest of environments. This and other features, including a high-speed autofocus made possible by a ring-type ultrasonic motor and high-speed CPU, ensure that the EF24mm f/1.4L II USM lives up to the high expectations of professional users.

*As of September 10, 2008. Among interchangeable SLR lenses with a focal length of 24 mm