The Sigma 24mm f/1.4 DG HSM includes the combination of three "F" Low Dispersion (FLD) elements and four Special Low Dispersion elements that help to achieve a marked reduction in chromatic aberration espandi...s, while a pair of aspherical elements, with one positioned in the rear of the lens, minimize a variety of additional distortions and aberrations. The 15-element-in-11-group optical design is poised to deliver consistent peripheral brightness and sharpness, even when working at the bright f/1.4 maximum aperture.