Sigma

20-40mm F2.8 EX DG ASPHERICAL FOR CANON

Super Multi Coating reduces flare and ghosting that tends to occur when using digital SLR cameras.
A Large F2.8 aperture wide-zoom lens from 20mm focal length.

SIGMA has created a new 20-40mm lens with F2.8 throughout its zoom range, from ultra-wide 94.5 degrees to near-standard 56.8 degrees angle of view, for photographers to shoot more creatively from various angles and zoom perspectives. With a fast F2.8 maximum aperture superior peripheral brightness is ensured. This lens is perfectly suited for indoor shootings even in dim light without worrying about blurring in photos. These features also make this lens desirable for use with Digital SLR Cameras.
30cm minimum focusing distance throughout the zoom range.
The lens’ 30cm minimum focusing distance is useful for closeups, giving photographers plenty of capability to use the zoom to adjust composition and concentrate on detail, as desired. Maximum magnification is 1:4.6. A short focus distance and a minimum aperture of F22 provides greater depth of field.
Aspherical lens compensates for aberration.
Aspherical lens elements in front and rear lens groups compensate for astigmatic and spherical aberration, respectively. By reducing aberration to an absolute minimum, this SIGMA lens overcomes a major impediment to zoom lens performance.
Sophisticated, yet simple to use.
Among the practical high-performance features of the lens are DF (Dual Focus) mechanism for optimal handling stability during autofocus operation; a wider-than-conventional focal ring for superior manual focusing operation; and an inner focusing system that eliminates front lens rotation during focusing, and allows use of the standard petal-type hood accessory, which is excellent at blocking out extraneous light.