I'm currently in the process of saving money for some photo gear - specificially 12-24mm sigma EX, 28-70 f/2.8 sigma EX (Aspherical DF version) and a canon speedlite 550EX. I've heard some stuff about how flashguns seem to have issues with some sigma lenses if they're trying to use TTL metering.. anyone got any info on this? I'm pretty much decided now on the lenses i'm going to buy as i've done extensive research on them and price-to-performance-wise they seem to be the best about to cover those focal ranges. (24-70 seems to be..less than adequate.) I'm also going to be buying a canon eos 20d sometime in april. Anyone experienced any issues/have experience with any of this kit? I'd appreciate your views. Thanks. Tom.