The Sigma APO 120-300mm f2.8 EX DG HSM Lens for Canon Digital SLR Cameras features a large aperture of f2.8 at the 300 millimeter focal length and is optimized for used with digital SLR cameras. This lens transforms a large-aperture f2.8 300 millimeter lens into a zoom lens that allows you to determine the picture composition you want without having to change your vantage point. It has two SLD (Special Low Dispersion) glass elements in front group and another SLD element in the rear group for excellent correction of chromatic aberration.
The latest in multi-layer lens coating technology and lens design reduce flare and ghosting, which is a common problem with digital cameras, and it also creates an optimum color balance through the entire zoom range. The lens' AF drive is equipped with a silent, responsive and high speed Hyper Sonic Motor (HSM), which also provides full-time manual focus function. Since focusing and zooming do not change its overall length, this lens is easy to hold and use. In addition, since the front of the lens does not rotate, a circular polarizing filter can be easily attached and used. High-speed focusing is possible when this lens is used with dedicated APO EX 1.4 x or 2x tele-converters (sold separately).
120-300mm F2.8 APO EX DG HSM lens. This lens transforms the classic large-aperture F2.8 300mm lens into a zoom lens that allows you to determine the picture composition without having to change your vantage point. Two SLD (the special low dispersion) glass elements in front group and another SLD element is used in the rear group for excellent correction of chromatic aberration. The new lens coating reduces flare and ghost, a common problem with digital cameras and also creates an optimum natural color balance. Since focusing and zooming do not change its overall length, this lens offers ease of handling. HSM ensures a quiet, high-speed, AF as well as full-time manual focus (for Sigma, Canon and Nikon mounts). Tripod Socket (TS-41) is supplied as a standard accessory. Circular polarizing filters can easily be used as the front of the lens does not rotate. When this lens is used with the 1.4x EX or 2x EX Apo Tele Converters (optional), it becomes a 168-420mmF4 AF telephoto lens or a 240-600mm F5.6 AF ultra-telephoto lens respectively.