Full-frame Canon EF-mount DSLRs and APS-C-sized models can both use the wide-angle zoom 16-35mm lens, which offers a 25.6-56mm equivalent focal length range. Throughout the zoom range, a constant f/2.8 maximum aperture provides reliable performance and superior light transmission. To preserve edge-to-edge sharpness and illumination, two large-diameter glass-molded dual-surface aspherical elements and one ground aspherical element reduce distortions and spherical aberrations across the zoom range. To reduce chromatic aberrations and get rid of color blurring around subjects' edges, two ultra-low dispersion elements are employed. To preserve light transmission and high contrast in harsh lighting, lens elements have been coated with both an Air Sphere Coating (ASC) and a Subwavelength Coating (SWC) to lessen backlit flaring and ghosting.