With a large maximum aperture of f/1.2 this professional lens is one of the fastest telephoto lenses in any class.  One aspherical lens element and two high-refraction elements give sharp images with little flare even at maximum aperture.  The floating system corrects coma for high image quality.  The EF 85mm f/1.2L USM is superlative for portrait and low light shooting; It's a highly acclaimed lens designed to separate creative pros from the crowd.