Not a pro, just an obsessive compulsive amateur. I started investing in this kind of equipment when I started photographing bald eagles on the Hudson River near my home. They come down from Canada each February and March. You need the "big guns" for that kind of photography, due to the distances involved, the frequently poor winter light from overcast skies, and the eagles' quick movements in flight. And I still don't have the equipment that's really up to the task, but that would require a $7,500 lens, and that ain't never gonna happen!