Sigma's Zoomy 18-250mm Lens Review/Rant: Better to Have 1 Lens or Many?

I was psyched when Sigma sent me an 18-250mm lens to test, because I am lazy and love the idea of a single lens that I can use to take most shots. At $530, it seemed like a decent price for that much range. But then I got to thinking... » 5/26/09 11:00pm 5/26/09 11:00pm