A couple weeks ago at Merritt Island, I had the opportunity to photograph a few Forster's Terns in flight. They can be very tough to catch! Normally when shooting birds I select only the center focusing point so that I can be more likely to get the bird in focus. But when I'm shooting birds in flight against a plain blue background, I frequently change my focusing mode to include all focusing points. The reason is simple: there really are only two places the camera will focus--on the bird or on the background, and the more focusing points I enable, the more likely I will get the bird in focus.