Try tracking kids with contrast detect
Faster AF with phase detect is something I couldn't live without. I only use contrast detect for landscapes. They move slow enough, typically.
I was just wondering how severe the problem may be, and if AFMA adjustments were just putting a band-aid on a more severe wound.
I picked up a 35A in March and have the 50A pre-ordered. I initially had AF issues with the 35A in that I felt my keeper rate was much lower than my other lenses. But I also noticed that the AF wasn't quiet. There was a clicking sound. I re-AFMA'd the lens, and the clicking sound went away (I think these are separate events). The AF is now both quiet (no clicking) and accurate at short distances. I have noticed that it is off at longer distances and have ordered the dock so I can AFMA multiple distances.
While the 35A is working well, that doesn't inspire confidence. Especially when combined with everything I am reading.
Everyone talks about the price different with the Sigma lenses, but that is just upfront costs. The savings will quickly disappear if the life cycle of the Sigma lens is half the Canon. Plus, one of the benefits of Canon's L lenses is how well they hold their value. If Sigma's aren't built as well and don't hold their value as well, then the true cost difference could quickly become negligible or even favor Canon.
All that said, I am past the point where I can return the 35A so I'll play with it some more. If I don't cancel my 50A order, I am planning on scrutinizing that lens a lot more before the return period ends.