I dun think the Canon is far off from the Sigma, frankly speaking maybethe diff is only about 10% at the most. And sometimes I am not able to tell at all.
On Friday I went down to TK photo to test the Sigma 50mm f1.4 - after having tested a few used ones on offer from classified as well as preowned resellers here. The older used ones performed erratically. ALmost always one in four or two in five shot continously will be out of focus.
The latest batch frm Sigma seemed to have solved this one single niggling problem. The one I tested was so sharp and accurate, it makes the EF50mm 1.4 look terrible.
Here is a shot taken at the shop itself straight out of the card - no post process, sharpen etc. just resized. (all shots at f1.4)
Here are some of my pet Jack Russel taken today (note the smooth bokeh quality)
I think they still have a couple more in stock so if you are looking for one. Hurry. Unfortunately, the price seems to have risen. So its not a cheap lens (I think its about S$100 cheaper overseas).
But I am happy to pay more to make sure I get one that really is a sharp and fast focusser.
BTW - I never thought that I will return to 3rd party lenses but for some reason, I have issues with the 3 on offer from Canon. 50L = too expensive and buggy; EFf1.4 = too soft wide open; EF f1.8 = effective only stopped down. I love the focal range of 50mm with FF camera. It will be in my bag all the time.
I recommend this lens highly to anyone looking for a decent 50mm.