The
EF 16-35mm f/2.8L II USM is a high performance, water-resistant, and
ultra wide-angle Canon L-series lens. It has been specifically designed
for improved edge-to-edge image quality that will meet the strict
requirements of professional and high-end amateur photographers. It
features 3 high-precision aspherical lens elements, each of a different
type: ground, replica and GMo for even better image quality than the
original EF 16-35mm f/2.8L USM. The circular aperture produces a
beautiful and natural background blur when shooting at wider apertures.
Other features include internal focusing, a ring type USM (Ultra Sonic
Monitor), and new AF algorithms for fast and quiet autofocusing.