Originally Posted by Expatriate
You must mean the 20-35. I've got 3 or 4 of the Sigma 2.8 lenses, and they treat me well. Also a Tokina 2.8. I just need at least a 17mm wide. Good to know aftermarket still compares well to Canon.
We did a number of tests at varying apetures and focal lengths. Center sharpness was pretty much indistinguishable for both lenses, but the Canon had noticably softer edges. The Canon 20-35L is supposed to be a very well regarded lens. Mitigating factor was that the lens was old and previously owned by a pro, but I wouldn't expect that to result in something like loss of edge sharpness.
Appologies for the total digression from anything biking related
