Sigma 50-500mm f/4.5-6.3 APO DG OS HSM SLD Ultra Telephoto Zoom Lens for Pentax Digital DSLR for 1,493.9

New Sigma APO 50-500mm F4.5-6.3 DG OS HSM. This is a 10x high zoom ratio ultra telephoto zoom lens incorporating Sigma's original Optical Stabilizer function. This lens covers a wide range of focal lengths from 50mm to 500mm ultra telephoto. The OS (Optical Stabilizer) function offers the use of shutter speeds approximately 4 stops slower than would otherwise be possible.