There is no doubt that the Canon 70-200 L IS 2.8 is the most popular telephoto lens we rent… but that doesn’t mean the Sigma isn’t a decent backup. It offers all the same features for 25% less money so if you’re on a budget, it’s worth the look. The autofocus isn’t quite as fast as Canon but otherwise it’ll put out a nice image! However if you are looking at Sigma, you might want the Sport version of this lens, which is like their ART lenses (ie top quality) but for longer telephotos. Confusing, right? We know.