Users of the Sigma & Sony 50 f-14

This looks like an uncharacteristically bad review for the S50/1.4, so I bet either a bad copy, or wasn't corrected for BF/FF issues(micro focus adjust or send to sigma for calibration, which is typical of all fast lenses not just sigma brand).

Also many of the "cons" listed here are cons of virtually all fast 50's.

My Sigma does show a little focus shift(again common with fast lenses) so you have to dial in a micro focus adjust to hit a mid ground. This really shows up shooting test charts more than actual use though.

http://kurtmunger.com/sigma_50mm_f_1_4_hsmid174.html

Kurt Munger's review has comparisons between the Sony and Sigma.

http://photography-on-the.net/forum/showthread.php?t=729368

Here is a comparison of the Simga 50 to the Canon 50/1.2L