Practically A Prime: The Sigma EX 12-24/4.5-5.6

Wide-angle has been the only area in which I've found the Canon EOS-10D system significantly lacking. The "crop factor" means that reaching even fairly common fields of view, such as 28 mm equivalent, involves significant compromises, and fun focal lengths much wider than that are much more difficult. That's why I was awfully excited when Sigma announced the 12-24 zoom -- and awfully disappointed when the first comments and test shots I saw were less than flattering. However, I ended up buying it anyway: some of the samples I saw appeared to show no major lens boogers, and I figured I could put up with some just for the possibility to get 20 mm equivalent, or thereabouts.

Popeye ready to go on the EOS-300D.

The Sigma EX 12-24/4.5-5.6, hereby christened "Popeye," because of its bulgy front element, occupies a unique niche among lenses. It's the first rectilinear 12 mm lens designed for 35 mm SLR's (yes, it's full frame). In fact, I believe it's only the second 12 mm rectilinear lens for the 35 mm format. The first was the Voigtländer Heliar ultra-wide 12/5.6 -- considered remarkable enough to rejuvenate an entire lens mount (Leica M39). This is something to keep in mind for the folks who gripe that Popeye isn't too bright. In other words, it breaks very significant new ground by the simple fact of existing.

Since the 14 mm rectilinears from Sigma, Canon, and Tamron are optically somewhat disappointing for the price, Popeye's only real competitors for ultra-wide with the APS-sized DSLR's are the "diagonal fisheyes" from Canon, Sigma, and Zenitar (not counting the Nikon 12-24 DX lens, which I've long been jealous about). These are smaller, brighter, cheaper, and optically excellent -- but unfortunately de-fishing them involves losing a good deal of resolution, gives a wider format to the image, and makes accurate framing difficult since the viewfinder no longer matches the final picture. Of course, you might not always want to de-fish; there's something to be said for the creative uses of the fisheye look.

Mmmmm... ultra wide.

Popeye only goes to 24 mm (38 mm equivalent). This makes it a rather a different beast from the other wide-angle solutions, the 17 or 18-to-something zooms, which come close to replicating the 28-to-short-tele range of classic 35 mm "normal zooms". It's a dedicated wide-angle instrument: in its uses, practically a prime.