I'm currently using consumer canon lenses 28-90 and 75-300 on my eos 20d, although i'm happy to stop these lenses down to get sharper images I still miss the freedom of having a faster lense. I have owned a couple of L series lenses (about 3 years ago then sold all my kit) and know just how excellent they are. Also I have owned sigma lenses and found the autofocus to be really bad (consumer lenses). The bottom line is, i'm looking for a cheaper alternative to L glass, so, how good are the EX series of lenses? Especially the autofocus.