The EF 135mm f/2L USM is a medium telephoto prime and a member of Canon‘s L-series of lenses. In regard to the optical design, the lens uses two ultra-low dispersion elements to control chromatic aberrations and color fringing for high clarity, and a Super Spectra coating has also been applied to suppress flare and ghosting for increased contrast and color accuracy. Medium-length telephoto prime is designed for full-frame Canon EF-mount DSLRs, however, it can also be used with APS-C models where it provides a 216mm equivalent focal length. Super Spectra coating has been applied to individual elements to minimize ghosting and flare for greater contrast and color neutrality when working in strong lighting conditions. Rounded eight-blade diaphragm contributes to a pleasing out of focus quality that benefits the use of shallow depth of field and selective focus techniques.