Cameras generally allow for two focusing functions: One-shot (or AF-S) and Continuous Servo (or AI Servo or AF-C). With one-shot the camera locks the focus. When you move your camera, the focus will not change. With continuous focus, the camera continues focusing when the subject is moving. Some cameras have an option that falls between these functions, i.e. the camera decides when to use continuous and when to use one-shot.
Find out where to change the focusing options on your camera and keep it on continuous. Also find out where to change the focusing point on your camera, so that you can move it off-centre to where you want the subject to be in the frame. If your camera does not allow you to change the focusing point, use one-shot, lock the focus and then move the camera. Concentrate on always focusing on the face or eye of the subject.
Some cameras allow the user to change the focusing activation button to the back of the camera. We use this extensively, and focus with our thumbs. By doing it this way, we can keep the focusing on continuous and stop it if we want to lock it on a subject, without having to go to one-shot.
How you can take a similar image
- Lens: Super telephoto lens.
- Settings: Low ISO. Maximum aperture.
- How: Keep the camera on continuous auto focus, so that it can track the subject as it runs. Use one focus point to make sure that your focus is accurate. If you use more than one, the camera could get confused and focus on the grass in front of the subject.