A tremendously flexible standard zoom for APS-C-format DSLRs, the Canon EF-S 17-55MM F/2.8 USM lens pairs the 27.2-88mm equivalent focal length range with a bright f/2.8 constant maximum aperture. Benefitting this design is a sophisticated optical layout, which includes both Ultra-Low Dispersion glass and aspherical elements to significantly reduce chromatic and spherical aberrations for improved clarity and sharpness throughout the zoom range. A Super Spectra coating has also been applied to individual elements to suppress flare and ghosting for increased contrast when working in bright environments. Beyond the optical attributes, this 17-55mm is also characterized by its advanced three stop-effective Image Stabilizer system to minimize the appearance of camera shake. Also complementing handling is a sophisticated ring-type USM, which provides quick, quiet, and accurate autofocus performance along with full-time manual focus override.