So my Sigmas arrived today! And had to run them up against my Canons... the results were interesting. Haven't tested corner performance though. All shots are 1/20s, ISO400, JPEG straight-out-of-camera, shot in my living room at night. I did view the images in Photoshop at 100%... here the compression will spoil them somewhat. So pixel peepers sorry if it's not a perfect comparison and these are after all my opinions only. First off, the Canon FL 55/1.2 @2.8. Tack sharp everywhere, but we already knew that Going wider, the Sigma 30 @2.8 Fabulous. Just wow. I was going to immediately resell this lens as my favorite 28/2 is so close yet faster, but now I'm torn. Canon FDn 28/2 @2.8 This was strange. It was nice and sharp, but much darker than all the others. When I shot it again at the middle notch between 2 and 2.8, it was exactly the same brightness as the other photos. Canon FD 24/2.8 @2.8 Very disappointing. I thought the 24 was my sharpest FD lens, but that impression appears to be because I constantly shoot my 28 at f2.0. It's poorer than the rest. Sigma 19/2.8 @2.8 Now we're in such wide territory that it's hard to really see the lens lettering. But this was as sharp as I could get it at 9.5x magnification, and it's softer than the 28, probably on par with the 24. Did I get a bad copy or is the 19 not as sharp as the 30?