Sigma 28-70mm f/2.8 EX DG

Manufacturer's Description:

"Compact, lightweight, yet robust, large aperture zoom lens

This compact, large and constant F2.8 aperture zoom lens and is ideal for digital SLR cameras. 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, maximum diameter of 74mm, filter size of diameter 67mm and weight of 510g."