Sigma’s APO 100-300mm f/4 EX DG is a telephoto zoom lens that allows photographers to take advantage of a long focal length for effect such as shortening perspective between the subject and background of blending subject that are in and out of focus. Three SLD (Special Low Dispersion) glass elements provide optimum color correction & sharpness throughout the entire zoom range. Compatible with Sigma 1.4 & 2x Tele Converters. This lens is an excellent performer in the EX professional series, incorporating key technologies such as apochromatic formulation for sharp images with precise color and a hypersonic motor for fast focusing. This product is discontinued. Consider using the 120-300mm f/2.8 EX DG APO HSM lens.