For the professional, a 16-28mm f/2.8 lens is almost a necessity, and this new AT-X 16-28mm f/2.8 Pro FX Lens for Canon from Tokina fills the bill very nicely. Designed specifically for Canon pro level DSLRs with a full frame (FX) sensor (such as the Canon EOS 5D Mark II), this super wide-angle zoom has 15 elements in 13 groups, using aspherical and SD super-low dispersion glass elements to reduce chromatic aberration and give maximum resolution. The silent DC motor allows the lens to focus quickly and quietly and works with a GMR magnetic AF sensor to increase AF speed even more. An exclusive One-Touch Focus Clutch mechanism allows switching quickly between auto focus and manual focus by snapping the focus ring forward for AF and back toward the camera for manual focus. And, it's possible to buy this lens without applying for a mortgage first.