I would like to Echo Kevshore's comments, I have a 200-400 mkI and am very happy with it. Although it has been significantly better since I have the focus motor and VR unit replaced. I have recently purchased a 500mm F4, I am still considering if I am keeping the 200-400. I bought the 500 for extra reach but the close focusing distance of the 200-400 means I might yet hand on to it, I will re-consider in a few months. My experience suggests as a close up lens for small birds the 200-400 is very good in some ways better than the 500mm, but the 500mm is sharper at distance and plays nicer with TCs.