Sigma 28-70mm f/2.8 EX DG AutoFocus Wide Angle Zoom Lens for Pentax AF Cameras

This is the world's smallest, large and constant aperture zoom lens and is idealfor digital SLR cameras. The power layout of the lens is specially optimized fordigital SLR cameras, and Super Multi Coating gives superb color performance whilst cutting down flare and ghost.

Two SLD elements and four aspherical lenses provide the ultimate correction against distortion as well as all types of aberration, especially spherical aberration. Its advanced optical design ensures high performance throughout the entire zoom range.

The use of aspherical lenses in the construction of this lens not only corrects aberrations but also produces a very small and lightweight lens design. Its compact, yet robust, construction has an overall length of 87.2mm (3.4in.), maximum diameter of 74mm (2.9in.), filter size of f67mm and weight of 510g(18.0 ounces). It has a minimum focusing distance of 33cm (13 in.) at all focal lengths and a maximum magnification ratio of 1:4.4 which is very convenient for close-up photography.

The inner focus system allows the lens to be focused without rotating the front element, therefore a Petal-type hood and circular polarizing filters can easilybe used.