70-200mm focal length 105-300mm equivalent focal length on APS-C cameras, 140-400mm equivalent focal length on Four Thirds / Micro Four Thirds cameras, 112-320mm equivalent focal length on Canon APS-C cameras F2.8 constant maximum aperture; F22 minimum Ring-type ultrasonic-type AF motor with full-time manual focusing 77mm filters 1.00m/39.37" minimum focus Available in Canon EF, Four Thirds, Pentax KAF3, Sony Alpha, Sigma SA, Nikon F (FX) mounts This large aperture zoom lens has improved optical performance and retains close-up ability with a minimum focusing distance of 100cm/39.4in and maximum magnification ration of 1:3.5. This lens is suitable for taking all type of subjects such as portraits, landscape, and close-up pictures. Two SLD (Special Low Dispersion) and three ELD (Extraordinary Low Dispersion) glass elements provide excellent correction for all types of aberrations. High image quality is assured throughout the entire zoom range. The super multi-layer coating reduces flare and ghosting. This lens incorporates HSM (Hyper Sonic Motor), which ensures a quiet and high-speed AF as well as full-time manual focusing capability. The lens design incorporates an inner focusing and inner zooming systems. The overall length of the lens does not change during focusing and zooming, ensuring convenient handling. A removable tripod collar (TS-21) is included as a standard component. When this lens is used with the optional 1.4x EX DG APO or 2x EX DG APO Tele Converters, it becomes a 98-280mm F4 AF telephoto zoom lens or a 140-400mm F5.6 AF telephoto zoom lens respectively.
I have both the Canon 70-200mm f/2.8 and this lens. The version I received is as clear and sharp as the Canon 70-200mm version and ALOT less expensive! The bokeh is as good. When photographing a local high school senior session recently, I shot the Sigma and my associate shot with the Canon lens. We dumped all our images together and aside from style, you could not tell which images had been taken with which lens. The bodies were both 40Ds. I have to look at the metadata to te..