"I never imagined that choosing the “right” ISO for wildlife photography would be the most controversial subject that I would teach. If you ask many pros about which ISO you should use, the most frequent response you will get is: “Choose an ISO based on what you are shooting”. If you are shooting a portrait of a bird or animal, choose a low ISO and when shooting action, select a higher ISO. My philosophy is to start out with the highest ISO your camera can handle and shoot with it from the start no matter what subject you are shooting. Why? "