The 12-24mm ultra wide-angle zoom design enables a combination of wider angle of view with optical characteristics optimized for use with every Nikon digital SLR. Two ED glass elements minimize chromatic aberration while three aspherical lens elements control distortion and reduce the overall size of the lens.
Our own comments A slightly more practical approach to wide angle photography is to choose a zoom. More distortion is introduced with a zoom, but this lens has won awards for managing to avoid most of those problems to some degree. At over a grand, you'd expect some good quality. This belongs in the Intermediate to Advanced photographer's bag.
Chromatic aberration is better than average across most of the focal length range, becoming high in the corners only at the 12mm extreme wide-angle setting. Vignetting is surprisingly low for a super wide angle, with a maximum of 0.75 EV falloff, dropping to 1/4 EV or less when stopped down by a stop or more at all but the widest-angle focal lengths. Distortion is relatively high at maximum wide angle, 1.08% barrel at 12mm, decreasing linearly until hitting a maximum of 0.28% barrel at 18mm, and then remaining at that level until 24mm.