Autofocus is a common feature on most 35mm SLRs and point-and-shoot cameras. There's really not much to using this feature; the camera does the work for you. All you have to do is look through the viewfinder to check whether the camera has focused correctly on what you want in the picture.

Autofocus can be a wonderful tool, especially for photographers with less-than-perfect eyesight. But there are times when autofocus can be a draw-back, especially when using long zoom lenses. The focusing mechanism of a zoom lens can chatter back and forth rather loudly while it's determining its sharpest setting. When you're in situations where these adjustments might be distracting, such as taking pictures of wildlife, you'll probably need to focus manually.

There is really no great trick to manual focusing, other than being able to see well enough to focus things yourself. Just adjust your lens from automatic focus to manual and turn the focusing ring. The viewfinder will tell you when the image you're focusing on is clear.

Most autofocus cameras have a nifty function called focus lock that lets you try various ways of composing a scene without having to refocus all the time. To use it, get your subject in the center of your viewfinder, where the autofocus is located. When you have the focus set, push the shutter or focus lock button (depending on your camera's setup) to lock it into place. Then recompose the scene. Keep in mind, however, that your distance from the object needs to stay the same. If you move forward or backward, you'll need to refocus.