This lens is a fast f/2.8 maximum aperture telephoto optimized for digital SLR cameras. The multi layer lens coating reduces flare and ghosting, which is a common problem with digital SLR cameras. ELD (Extraordinary Low Dispersion) glass elements reduce chromatic aberration to a minimum and also ensure sharp, quality images of high contrast. It creates an excellent image quality for both 35mm film and digital SLR cameras. A 46mm drop-in filter holder in the rear part of the lens barrel facilitates the use of different filters, including a polarizing filter.
The HSM models (Sigma, Nikon and Canon mounts) provide fast, silent AF function as well as full- time manual focus override. It incorporates an inner focusing system, which enables the overall length of the lens to stay the same while focusing, ensuring convenient handling and ease of use.
By simply adding an optional APO teleconverter (sold separately), this lens can be used as a 420mm F4 AF ultra-telephoto lens with a 1.4X EX teleconverter, or a 600mm F5.6 AF ultra-telephoto lens with a 2X teleconverter.
