If you’re shooting a stationary subject from a stationary camera, focus is pretty dang easy. But when one object starts to move, it gets a bit more difficult. If both the subject and camera are set in motion, you begin playing a game of chase that often leaves the shot slightly soft with rack focuses as you try to find the subject clearly.
The Myth of Autofocus
If you read the marketing materials that accompany most DSLR cameras, they promise useful autofocus features. Just turn on the intelligent tracking in your camera and the camera will lock on a face, follow your subject, and keep the subject in focus. Sounds great, right? In theory, yes.
Unfortunately, these controls are pretty useless in practice. Relying on autofocus will result in the camera making continuous adjustments. Chances are it will latch onto the wrong subject. Pan or tilt the camera just a little and suddenly the camera may start searching for focus.
Film and video professionals do not use autofocus when shooting video. Sure, it’s fine to engage autofocus to lock in a clear shot before rolling, but don’t expect the camera to maintain focus for you. It just doesn’t work; even the best systems make your video look amateurish and jarring.
So how do you get shots that are in focus? The same way that you get great composition—practice, practice, practice. With time, you’ll get the hang of things. Turning your focus ring will get easier with time. You’ll master the small adjustments needed to smoothly transition between focus points.
Of course, there’s nothing wrong with practicing a tough shot either. A film or video pro will often rehearse a complex shot, having the subject stand on certain marks or move through a location slowly. Additionally, don’t be afraid to repeat a shot a few times. Getting multiple “takes” improves your chances of getting the right footage and gives you choices when you sit down to edit.
Change Your f-stop
The more you open your aperture, the more light you allow into the camera. That’s good news when shooting in low light except that the depth of field gets shallower. If you’re having a hard time focusing, close down the aperture. Switching to f/8 is immensely easier to focus than f/1.4.
Of course, making a change in aperture will dramatically change your exposure. To compensate, you can make these changes (which are in order of preference):
- Add more light to the scene. Use video or available lights, change locations, open the blinds, and so on. All of these actions will give you more light to work with.
- Change your ISO to increase the sensitivity of your camera. Many modern DSLR cameras can shoot at ISO 1200 or even 1600 without introducing too much noise.
- Lower your shutter speed to allow more light to reach your camera sensor. If you don’t have a lot of action in the scene, switching from 1/50 or 1/60 to 1/30 will dramatically increase the light without much impact on image quality.