During our dolphin watching tour I used two camera bodies, one with a 400mm and the other, a 17-40mm. Surprisingly enough, the wide angle turned out to be the better choice since the dolphins swam so close to the boat. When this bottlenose breached, I was looking in a different area. I heard a gasp from a few people on the boat and immediately turned and fired three shots in less than a second. The shutter speed was set to 1/1600th to freeze the action.