Sigma 50mm f1.4 @ f1.4 -> WOW
This was the first lens I bought from Sigma, for my Canon 30D. It has worked very well. I did a fairly large project with it over the last couple years photographing paintings for an artist.
Here is a link. Beware lots of photos here, and resolution is limited for protection of the images: http://www.mike-yengo.com/
I made one of these into a 30x40 wall mount print (10508, first shot in the first gallery, thru Meridian Pro on the web) and it turned out well. Lots of bayer artifacts in the fine details but no issues at all with sharpness.
I wish I had one for my SD1, but I have the 85mm F1.4 instead, and certainly no complaints about this lens either!