I want to get a lens as a birthday gift for my daughter. I've decided to go with a 70-200mm. She is currently "borrowing" my Canon 70-200mm f4 non-IS which is the least priced of the 70-200's. I believe the most expensive is the Canon 70-200mm f/2.8L IS at around $1,00 or so. And then there's the f4 with IS around $1K. Can I get a recommendation or 2 for a non-Canon version of the lens that would save some $$. Thank You.