Gary Wolstenholme takes a look at this popular lightweight ultra-wide angle zoom lens, which has a constant aperture of f/4, an Ultrasonic focusing motor and sealing against the elements.
Superb performance in the centre throughout the range; Well built; Lightweight
Sudden softness in the corners may disturb full-frame SLR users; Distortion difficult to correct entirely at 17mm; Falloff at 17mm