Common Tern - Sterna hirundo

Obtaining pictures of terns in flight and diving for food for me has not been easy.  On my last birding expedition.  There were a number of common terns fishing just off the beach at Third Beach in Middletown, Rhode Island.  I first observed their flight pattern .  Utilizing my Nikon D800, and my Nikkor 500 F/4 lens set on a Jobu gimbal mount on my Redged tripod, I pre-focused my lens and soon as I had a tern in focus, I would bump focus, utilizing the cameras back focusing button, and continuous autofocus I would start photographing.  Although I caught the tern going into the water and coming out of the water, I did not photograph the tern catching any fish.