A big thread to go through! Excuse my laziness, but can anyone comment on the AF in low light, aka shooting live gigs? Crammed right up on the stage, I need something wider than my 30mm. Right now it's a toss up between the Canon and the Sigma since everyone who has reviewed the lens downplays the Sigma's focus speed in comparison to the Canon, but there is no mention of accuracy in low light. I don't want to miss the shot! Can anyone help me out?