Canon EF 20-35mm f/3.5-4.5 USM Ultra-Wide-Angle Zoom Lens    

Highly portable lens with high optical performance and light weight of 12 oz. (340 g). A very practical ultra-wide-angle zoom. The large front lens group minimizes peripheral darkening, and the flare-blocking diaphragm minimizes flare. Also, with lens group 2 being the zoom group, distortion is corrected.
Specifications
Construction 11 groups /12 elements
Angle of view 94° - 63°
F stop range 3.5-22 (4.5-27)
Closest Focusing Distance 0.34m / 1.1ft.
Maximum Magnification 1:7.7
Filter Size 77mm
Dimensions (Length x Diameter) 3.3" x 2.7"/ 83.5 x 68.9mm
Weight 12oz. / 340g