Snowy Owl in flight
Plum Island, MA. After heavy crop.
Okay, here's story. The snowy owl was standing in the marsh about 150 feet away from me. It was so far that my 400mm f5.6 lens was way too short. Then I had to attach on 1.4x converter for reach but lost autofocus as the result. While I was shooting using live view and manual focus, the snowy took off and flew towards me!! Without auto focus, I could only take several shots (including this one) and watching. The snowy came to only 10 feet away from me, picked up something on the ground and flew away.
That was the point when I made up my mind to buy a 500mm f4 lens. :)