[Dr_Jones]

So im crossing Boston Common on Sunday and i see a hawk perched on a steeple (park and tremont) about 100' up and maybe 150' to 200' away. Had my second hand 70-200 f/4L and set the camera up for fast shutter (faster than 1/1000th) and reasonably wide depth of field (online calculator is telling me about 70' deep).

I try to use the center point 1 shot AF to get the bird crisp but im really disappointed with how soft all the shots turned out...the bricks on the building seem reasonably sharp but not so much on the bird. The bird dives legs extended talons out and grabs a pigeon off of the sidewalk. i follow him all the way down...i did not have time to get the AF in servo and not one shot has the bird crisp.

This is a second hand camera and a second hand lens? how would you diagnose the weak link...or is it just that the range is too long to expect sharpness for 200mm...or is my technique incorrect (stop down a bit and use a background object reasonably close to the bird get focus). This Fa-qer was really moving...