Dec 30 2005 (May 18 2007 Updated)

At f1.4: The Sigma is sharper and renders better contrast, while the Canon produces more haze and a "soft focus-like" effect at its widest aperture. The Canon is very useable IMO but the Sigma is better here at f1.4; in fact, I've yet to use a better lens at f1.4 than this EX lens. You can shoot with confidence wide open, unlike other glass. From wide open, there is a noticeable "jump" from f1.4 to f2 for both lenses, as sharpness and contrast increase. This pertains to both center and edge performance. Both are excellent optics that, by f2.8, deliver EXTREMELY impressive color and detail.

AF: The Sigma's ring-type HSM makes for swift, silent, and accurate AF while the Canon's (inferior) micro USM produces AF that is fairly quiet and quick. The Canon's focus ring extends physically in and out while the Sigma's does not. This is a significant advantage to the EX.

Build: Here the Sigma EX truly separates itself from the Canon EF lens. The Sigma has a solid, robust feel to it while the Canon indeed feels plasticky and less durable. The build of the Canon is certainly better than its 50 f1.8 MKII sibling, but it isn't up to the EX's level. The Sigma's better build can also be felt when turning the focus rings on each lens: the Canon has very little dampening (almost too loose) with some "play" in it, while the Sigma has good tension and no "play" at all. However, the EX focus ring (when turning manually back and forth) has some "grit" to it which makes it less smooth than, say, the 35L.

Weight: The Sigma checks in at 14oz and the Canon at 10oz.

Usability: On a 1.6x body, I find the Sigma 30 MUCH MORE useful than the Canon 50. In fact, I rarely use the 50 anymore as I will either use the 30 or 85. But practically-speaking, the 30 (48mm FOV) is as good as it gets for a standard APS-C prime.