When photographing wildlife, you have to think very fast. You don't have time to emote or, in many instances, even take your eyes away from the viewfinder. Things happen too fast. This very young orangutan in Indonesia is an example. It was squirming in its mother's arms, and every fraction of a second the composition changed, the expression changed, and do did the focus. Therefore, watch your wildlife subjects through the viewfinder and be ready to shoot a lot of frames. Put the drive on 'multi' so you can shoot several frames per second if you have to. I took this picture with a 300mm lens at f/2.8, a shutter speed of 1/250th of a second, 400 ISO, hand held