Why is the 17-85mm f/4-5.6 EF-S IS USM(Amazon-$484.99) more expensive than the 28-135mm f/3.5-5.6 IS USM(Amazon-$384.95)? Not only does the latter zoom further but it opens wider and yet it's $100 cheaper. I have a two year old daughter and a three year old dog, neither of which sit still for longer than 5 seconds. Would either of these lenses be good for "candid" photography? ANY suggestions for a lens would be greatly appreciated. I have around a $500 budget and it would be for a 30D. There seems to be three categories; cheap, expensive and "L". Is there a L lens that would be worth saving longer for? (seeing as how I'm half way there, generally speaking) Another $500 would put me into November before I had it saved up. Would it be worth the wait or maybe I should just get two or three cheap ones and learn how to use them????