Pairing a favored super telephoto focal length with a bright f/2.8 maximum aperture, the EF 400mm f/2.8L IS II USM is a Canon L-series optic well-suited for outdoor, wildlife, and sports applications. 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. Two fluorite elements are used in the optical design to help reduce color fringing and chromatic aberrations for high clarity and color accuracy and a Sub Wavelength Coating has 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 four 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. 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.