Pairing a favored super telephoto focal length with a bright f/2.8 maximum aperture, the EF 400mm f/2.8L IS III USM is a Canon L-series optic well-suited for outdoor, wildlife, and sports applications. This version III of this prized lens features a lighter weight design along with a sophisticated optical layout and updated handling capabilities. The fast maximum aperture enables extensive control over depth of field for isolating subjects using selective focus, and it also benefits working in difficult lighting conditions. Both Super UD and fluorite elements are used in the optical design to help reduce color fringing and chromatic aberrations for high clarity and color accuracy, and Super Spectra and Air Sphere Coatings have been applied to individual elements to suppress flare and ghosting for increased contrast and color neutrality when working in backlit conditions.

Beyond the optical attributes, this 400mm f/2.8 is also characterized by its advanced five stop-effective Image Stabilizer system, which has three separate stabilization modes to suit various shooting applications. Also complementing handling is a sophisticated ring-type USM, which provides quick, quiet, and accurate autofocus performance along with full-time manual focus override. A customizable electronic focusing ring further contributes to precise manual focus control, by affording three focusing sensitivity levels for different applications. Additionally, this lens is weather-sealed for use in trying environmental conditions, and it has a removable rotating tripod collar to benefit working atop a tripod or monopod.