Sigma’s APO 300-800mm F5.6 EX DG HSM is another unique lens in the line of Sigma offerings. An ultra telephoto as no other camera or lens manufacturer offers the serious photographer! Featuring a constant aperture of F5.6 throughout the entire zoom range, this lens is ideal for photographing wildlife when there is no way of controlling the distance of the animal to the camera. With a simple turn of the zoom ring, the photographer can instantly adjust the composition of the image without moving or disturbing the subject. Similarly, the zoom accommodates sporting photography such as soccer or surfing where the rapidly changing distance of the action requires massive changes in focal length in a matter of seconds. Two SLD (Special Low Dispersion) glass elements provide optimum color correction & sharpness throughout the entire zoom range. At the rear of the lens, a drop in 46mm filter holder is provided so that the photographer can easily add inexpensive color correction or light balancing filters. A perfect lens for surveillance use, its stealth black finish is unobtrusive and easily concealed.