The 56mm f/1.4 DC DN is part of Sigma's Contemporary series of lenses. The lens is characterized by its bright f/1.4 maximum aperture, which suits working in difficult lighting conditions and also off espandi...ers improved control over depth of field for isolating subjects and working with selective focus techniques. The optical design utilizes two aspherical elements and one SLD element, which help to reduce both spherical and chromatic aberrations for greater sharpness and clarity.