Good shots! No substitution for length when shooting birds. I picked up a used 400 f2.8 years ago. Even tho its a heavy bugger for me now I keep it for those times I want to shoot some flying buddies. I have to put a 2X or at least 1.4X on it and shoot on a tripod.Sigma 150-600mm. I've always wanted a Canon EF 600 but just can't justify it with my limited talent, plus the Minster of Finance would beat me silly.