One of the most well-known rules in photography is the Rule of Thirds--the guideline that says you'll get better pictures if you place the subject off to the side rather than dead smack in the middle of the frame. Compare the two photos below, for example. Shifting the camera a little when you take your shot can make a lot of difference.
That's great, but many cameras simply focus on whatever's in the center of the picture. So if your subject is somewhere else, you'll end up with an out-of-focus shot. What to do?
Use Focus Lock
You're in luck. Virtually all digital cameras have a two-step shutter release: Press lightly on the button (so it only goes halfway down), and you set in motion a series of events in which the camera prepares to take the picture. Most importantly, the camera measures the distance to the subject in the autofocus zone (usually the center of the viewfinder) and locks the focus. As long as you keep some pressure on the shutter release, you're free to reposition the camera and compose the shot any way you like. When the scene is composed to your liking, just press down the rest of the way.
Focus lock is a common and powerful way to lock the focus on a person, then move the frame slightly to put your subject in the Rule of Thirds "sweet spot."
Use Focus Zones
A better alternative might be to use a focusing zone, if your camera has that feature. What's a focusing zone, you ask?
Well, instead of only having one point in the middle of the frame for focusing, your camera might have five or more arrayed around the viewfinder. Use a control on the back of the camera to select one of the zones, and that's the point that your camera uses to focus--to the left, right, top, or bottom of center. That way, you never need to focus lock and recompose. Just set the active focus zone over the subject and take the shot. With practice, you can change focus zones without looking away from the scene in the viewfinder.
Why Focus Zones Are Better
Why use a focus zone instead of focus lock? Sometimes it's just a personal preference. At other times, though, it can be a question of focus accuracy. Imagine that you focus on something in the middle of the scene, then twist your body slightly to recompose the shot, as in the illustration.
The camera is now set to focus at a closer distance than the true distance to the subject. In some situations, that small geometric glitch can make the difference between "kind of sharp" and "really sharp." As a result, I think that using zones is usually better than the trick of using focus lock and then moving the camera.
Keep in mind that this won't make any difference if the subject is far away, so the camera is focusing at infinity. But for scenes in which the subject is close at hand (like within a few dozen feet of you), this technique can help make your photos a little bit sharper.
Hot Pic of the Week
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This week's Hot Pic: "Rose at Night," by Elizabeth Wesson, Cedar Hill, Texas
Elizabeth took this photo with a Nikon D50. She says she had noticed that her rose bush had just bloomed, but didn't get a chance to take a picture during the day. "So," she says simply, "I grabbed my camera and took this night photo."
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This story, "Focusing When Your Subject Isn't in the Center" was originally published by PCWorld.