Thank you Brian. Weight is an important factor. I feel like the range that I will use most will be the 70-200 or even longer. I would like the 2.8 but it's way to heavy. I'm thinking of getting the f4 version but maybe I should get the 70-300 instead? I've read nice reviews on both lenses. That would keep the weight down and free up funds for a wide angle lens. Too many choices!