[obican]

Is it worse than with fast Canon glass? I didn't count more blurred results with one or another brand, most of the times it was also me being in a hurry or haven't fully understood how to autofocus. One difficult candidate was the 18-35/1.8, when going wide there was just too much stuff in the AF frames. But that was on an APS-C DSLR. I think, on Sigma's sd quattro the lens is always tack sharp if the AF has had enough time  :lol:

 

With Sigma AF on 6D are simply too many variables and the whole process is time consuming. You have to remove the lens every single time and put it on the dock to run the software. Also I'm not even so sure that that every AF point on the Canon needs the same amount of microadjustment.

 

What makes things even more complicated and frustrating is that I've seen that Sigma both back AND front focus when I had handled it. It's like the AF motor doesn't disengage when the AF is locked and it moves a bit more. I always had my doubts on this but I saw a few other individuals claim to see the same behavior. 

 

Just too much trouble for what is essentially a 50mm f/1.4 lens. It takes the same photos as my FDn 50/1.4, just sharper and less CA and stuff. Doesn't make you a better photographer in any way, doesn't really let you make THAT shot that you couldn't with any other AF 50/1.4. and is much heavier.