Sigma AF 18-35mm f/1.8 DC HSM ART Lens for Nikon SLR

17 elements in 12 groups. F16.72mm Minimum aperture. 72mm Filter Size. 76.5 - 44.2 Angle of view (SD1). 28cm/11.0in Minimum focusing distance. 9 diaphragm blades (Rounded diaphragm). 1:4.3 Max magnification ratio. Dimensions 78mm x 121.0mm/3.1in. x 4in.