Hey guys. I'm looking for a new walk-around lens, and currently it's narrowed down to either: Sigma AF 18-200mm f/3.5-6.3 DC OS and Sigma 17-70mm f/2.8-4.5 DC IF Macro The max range doesn't matter too much since I already have a 70-300mm, and the macro doesn't matter either because I plan to buy a Canon 100mm macro lens in the future. The only things that matter is that one has image stabalization, while the other has a lower stop. Which is more important in getting a sharper image? P.s. What are "DC" and "IF"? Thanks.