SWMSilent Wave Motor AF-S NIKKOR lenses feature Nikon’s Silent Wave Motor (SWM), which represents a significant advance in AF lens technology. SWM uses ultrasonic vibrations—rather than a gear system—to focus the lens, providing incredibly smooth, silent and precise autofocus operation. ED (Extra-Low Dispersion) Glass An optical glass developed by Nikon that is used with normal optical glass in telephoto lenses to obtain optimum correction of chromatic aberrations. AS AS stands for Aspherical lens elements. This type of lens utilizes non-spherical surfaces on either one or both sides of the glass in order to eliminate certain types of lens aberration. M/A Select NIKKOR lenses have a focusing mode which allows switching from automatic to manual focusing with virtually no lag time by simply turning the focusing ring on the lens. This makes it possible to seamlessly switch to fine manual focusing while looking through the viewfinder. IF Lens A NIKKOR lens in which only the internal lens group shifts during focusing. Thus, IF NIKKORS do not change in size during AF operation, allowing for compact, lightweight lenses capable of closer focusing distances. These lenses will be designated with the abbreviation IF on the lens barrel. Specifications Mount Type Nikon F-Bayonet Focal Length Range 12-24mm Zoom Ratio 2.0x Maximum Aperture f/4 Minimum Aperture f/22 Format DX Maximum Angle of View (DX-format) 99° Maximum Reproduction Ratio 0.12x Lens Elements 11 Lens Groups 7 Compatible Format(s) DX FX in DX Crop Mode Diaphragm Blades 7 Distance Information Yes ED Glass Elements 2 Aspherical Elements 3 Super Integrated Coating Yes Autofocus Yes AF-S (Silent Wave Motor) Yes Internal Focusing Yes Minimum Focus Distance 1.0 ft. (0.3m) Focus Mode Auto Manual G-type Yes Filter Size 77mm Accepts Filter Type Screw-on Approx. Dimensions (Diameter x Length) 3.2 (82.5) x 3.5 in. ( x 90 mm) Approx. Weight 16.4 oz. (465 g) Supplied Accessories HB-23 Hood 77mm lens cap Rear lens cap