This fast design suits working in a variety of lighting conditions throughout the zoom range and also affords greater control over depth of field. Further distinguishing itself, this lens sports four aspherical elements and three extra-low dispersion elements in order to control spherical and chromatic aberrations for greater sharpness and clarity. A Nano AR Coating has also been applied to further reduce surface reflections and flare for improved contrast when working in bright and backlit conditions. Benefitting the optics, this lens also sports an XD Linear Motor system that is quick and quiet, and also lends more responsive control for manual focus operation. The lens also has a dust- and moisture-sealed design, along with a fluorine coating, to support shooting in inclement conditions.