I had owned the original Canon 400mm DO previously and was never thrilled with it so I sold it. With the release of V2 I rented first and was so impressed I decided to buy one. It is the perfect combination of weight,size,and reach for my style of shooting. It also works well with a 7D II and a 1.4X to give you a 5.6 at 560 plus crop factor. I am extremely glad I bought it .