How to Use Autofocus


Right Image:
Canon EOS D30, Tokina 300mm f-4 ATX lens
1/350 sec at f-4, aperture priority. Multi-pattern metering and autofocus. Bogen monopod and ball head.

Autofocus is without a doubt a very useful feature, but having an AF camera doesn't guarantee sharp pictures unless you learn
how to use it. Like other features such as different metering system, autobracketing
high speed motor drives, autofocus should be used when it is really necessary and turned off when not needed. I don't always use my built-in camera meter, or shoot at 5 frames per second all the time. I use these features among others depending on the situation, and autofocus is no different.

Autofocus with tracking has made high speed shooting much easier. You no longer have to worry about focusing while shooting birds in flight. Today's autofocus cameras do a good job most of the time. For people with less than perfect vision, or in low-light situations, AF is a great aid. At times however, manual focus is the only way to go. I switch to manual focus when I'm shooting stationery subjects such as a landscape, architectural, still life, or even portraits. One of the problems with autofocus cameras is the point of focus that you need, usually falls outside the AF indicator. You have to first focus, press and hold focus lock, recompose your shot, and take the picture. If you need to readjust your tripod or exposure, this whole procedure can become really difficult. In situations like this, manual focus is much easier. Actually, going totally manual, and that is, manual focus, manual mode, and ignoring your built-in meter is much easier and faster in some situations. If I'm shooting a landscape or a building, I always use manual focus and manual mode. This gives me much more control over my pictures, and if I'm shooting a middle tone subject in bright sun, I ignore my meter and use Sunny F-16 rule. By using manual focus, I can decide my point of focus and figure out depth-of-field and adjust much faster and easier than using autofocus.


Right Image:
Canon EOS D30, Tamron 70-210mm f-2.8 lens
1/750 sec at f-5.6, aperture priority. Multi-pattern metering and autofocus.

When you use autofocus you force yourself to use what your camera has focused on, but your camera doesn't know how you want your pictures to be. When photographing a landscape, a building, or similar subjects, compose your shot and switch to manual focus and find a point that will give you the depth-of-field you need.
You can easily adjust focus without having to move your camera around. Autofocus is best used with fast moving subjects. When shooting wildlife or sports, having an autofocus camera with tracking can make difficult shots much easier. Cameras with larger AF indicators allow faster focusing and tracking. You can quickly lock on target and shoot. Autofocus can come in handy in many situations, but you have to learn when and how to use it. Don't think just because your camera is capable of fast autofocus, it can give you the pictures you want. Even the best models need to be used in manual focus sometimes.