This telephoto zoom lens provides a large constant f/4 maximum aperture at all focal lengths. The use of Apochromatic design and 4 SLD (Special Low Di

This telephoto zoom lens provides a large constant f/4 maximum aperture at all focal lengths. The use of Apochromatic design and 4 SLD (Special Low Dispersion) glass elements give full correction of chromatic aberration and provide a high level of optical performance. The AF drive for the Sigma SA mount is equipped with the silent, responsive and high speed Hyper Sonic Motor and provides fulltime manual focus override. 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. Handholding is easy since focusing and zooming do not change its overall length. 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 new lens are lead and arsenic free ecological glass.