You are at the St. Augustine Alligator Farm with a 70-200mm lens in your hands. Your camera is (as it should be) set at zero exposure compensation. A woman screams. A gator--in full sun--has just grabbed an adult Cattle Egret. Let us know what camera you are using and how you would compensate. Remember, if you hesitate, you miss the image as the creature is headed for the water to keep others of his ilk from grabbing its meal. (See item two below...)