Originally posted by tkindred Anyway, do you guys think the extra cost of the Pentax 12-24 is justified over the Sigma 10-20?
Depends on what you're looking for in a lens. In terms of resolution, distortion, and CAs, while one lens may be a little better than the others, for all practical purposes, there's not much to choose between them on those grounds. The main differences are the focal lengths and color rendition. The DA 12-24 has outstanding micro-contrast, color rendition, and overall rendering, leading to images with intense, rich, deep blues and luscious dark greens. The Sigma is also very good, producing bright yellows, oranges, and rich browns.
The choice between these lens really comes down to which focal lengths one prefers (10 to 12 or 20 to 24?) and which color rendition scheme and overall rendering one finds most pleasing. If one finds 20 to 24 more useful than 10 to 12 and has a strong enough preference for the rendering and colors of the 12-24 to justify its greater cost, then that's the lens to get. Otherwise, the 10-20 is the better choice.