|Sigma 100-300mm f4 EX APO IF HSM is one of several EX-Series lenses. This telephoto zoom lens provides a large constant F4 maximum aperture at all focal lengths. The use of Apochromatic design and 4 SLD (The Special Low Dispersion) glass elements (two SLD glass elements are utilized in the front lens group and two in the rear group) for full correction of chromatic aberration and providing a high level of optical performance. The AF drive for Sigma SA, Canon and Nikon cameras is equipped with silent, responsive and high speed HSM (Hyper Sonic Motor) as well as fulltime manual focus. A removable tripod mount is provided with the lens. This lens incorporates an internal focusing system, which eliminates front lens rotation, allowing the use of a Perfect Hood and easy to use circular polarizing filter. Since focusing and zooming do not change its overall length, this lens is easy to hold and use. It is also possible to use this lens with Sigma 1.4x EX and 2x EX APO Tele Converters to make ultra tele-zoom lens. The lens materials used in this lens are lead and arsenic free ecological glass.