A wide-angle lens is an indispensable piece of equipment for a wide range of photographers. Those using the Nikon system should consider picking up the Nikkor AF-s 12-24 (18-36 35mm equivalent). Photozone recently reviewed the lens stating,

“The Nikkor AF-S 12-24mm f/4G IF-ED DX proved to be a very good performer. Its center resolution figures are exceptionally high and apart from 12mm @ f/4 the border quality is also impressive though a little less field curvature may be desirable at 12mm. CAs as well as the distortion characteristic are very good for an ultra-wide zoom lens whereas vignetting is about average due to the reduced APS-C image circle. The build quality is, in principal, very fine but you would usually expect a little more from a lens in this price class. The primary competitor is probably the Tokina AF 12-24mm f/4 AT-X Pro – a lens which is just as sharp but with a higher degree of CAs and worse flare in contra light – all at less than half the costs and combined with a better build quality. Costs aside it’s a close race between the two with a slight edge for the Nikkor regarding optical quality. When taking the very different price tags in account the decision may be a little more complicated.”