Standard zoom offers a 36-79mm equivalent focal length to realise a versatile range of fields of view to suit a wide variety of shooting applications.Constant f/4 maximum aperture offers consistent performance throughout the zoom range.One Super ED element and one ED element greatly reduce chromatic aberrations and colour fringing throughout the zoom range for greater clarity and colour accuracy.Three aspherical elements control field curvature, distortion, and spherical aberrations in order to maintain a high degree of sharpness and accurate rendering.A linear AF motor is used for quick, quiet focusing performance to suit both photo and video applications. Also, an internal focusing design maintains the overall length of the lens during focusing and promotes quicker focusing movement.Optical Image Stabilisation system compensates for up to five stops of camera shake to help realise sharper imagery when shooting handheld.Rounded nine-blade diaphragm contributes to a pleasing bokeh quality.Physical aperture ring allows for intuitive adjustment over exposure settings and incorporates a C (Command) position to permit camera-based aperture setting.Dust- and weather-sealed magnesium alloy construction enables working in harsh climates and temperatures as low as 14F.