Hey I've been trying to get out and shoot pictures a bit more lately and I've been reading that the lens I have, the 70-300mm EF is a notoriously soft lens especially out past 200mm. What I am wonder is with my limited budget would I better off getting a sigma lens to save a bit of money. Do the Sigma lenses provide good IQ? I think I should be able to swing $500-$600 for a new lens. So what do you guys recommend?