TheSigma 200-500mm f/2.8 EX DG APO IF Lensis a massive ultra-telephoto zoom lens that offers an impressive fast f/2.8 aperture throughout its entire zoom range, all the way up to 500mm. Combined with the included dedicated high-quality 2x teleconverter, this lens can be converted for use as a 400-1000mm f/5.6 lens. Now combine this with an APS-C sized digital SLR camera, and you're looking at approximately a 300-750mm f/2.8, or a 600-1500mm f/5.6 (with 2x teleconverter) lens.
This lens covers the widely used 200 to 500mm focal length range, and maintains its fast f/2.8 aperture over its entire zoom range. SLD (Special Low Dispersion) glass and three ELD (Extraordinary Low Dispersion) glass elements provide excellent correction for all type of aberrations, and assure a high level of optical performance throughout its entire zoom range.
Shooting distance and focal length are displayed on the lens' LCD panel, which is almost a necessity with a lens of this size. In addition, a dedicated BP-21 Li-ion battery is used to power-assist the zooming and AF operation. This battery is built into the lens barrel.