After taking some shots of Brad and a student of ours photographing a mature bald eagle at Ludington State Park, I switch to my big lens just in time to watch the eagle take off after an immature eagle swooped down at it. The mature bird flies over my head so close that I have to shoot without looking through the viewfinder to track with it. Awesome! F4.0 at 1/4000, ISO 800, 500 mm lens at 500 mm