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Your focusing options depend on the type of digital camera you own. Cameras aimed at the casual picture-taker offer autofocusing; models designed for professionals and photography enthusiasts offer a choice of both autofocusing and manual focusing.
Choosing an autofocus mode
Most digital cameras offer at least two autofocus modes: normal and macro. Some models offer a third mode, infinity. Here's a quick rundown of these modes:
- Normal autofocus mode enables you to focus on subjects within a range of distance that's appropriate for normal photography. Usually, that range extends from several feet in front of the lens to infinity. This mode works well for portraits.
- Macro focusing enables you to focus on objects very close to the camera lens. The close-up focusing range varies from camera to camera; with some models, you can get as close as an inch from the lens. Most cameras label this focus option with a little flower.
- Infinity focusing locks the focus at the far end of the standard autofocus range so that objects at a distance appear in sharp focus. Sometimes labeled with an infinity symbol, this setting is great for landscape photos.
Because the focusing ranges for each mode vary from camera to camera, check your digital camera's manual to find out what mode is appropriate given the distance between you and your subject.
Finding the focusing area
To set the focus for a picture, your camera calculates the distance between the camera lens and objects within the frame. The specific area of the frame that's used to make this measurement depends on your camera.
Some cameras offer several focus area options:
- Multi-point focusing considers objects throughout the frame.
- Center-spot focusing sets the focus only on the object at the center of the frame.
- Adjustable-spot focusing works just like center-spot focusing, except that you can vary the location of the spot-focus point — moving it from the center of the frame to the left side of the frame, for example.
Most cameras offer the second option, center-spot focusing, as the standard focusing area. The focus point is usually indicated by a marking at the center of the frame — a circle or brackets, for example. The marking appears in the viewfinder and on the monitor, as shown in Figure 1.
Figure 1: Focus markings show the area of the frame used to calculate focusing distance.
 | Whatever focusing-area option you choose, be sure that your main subject is located within the boundaries of that area when you compose the picture. Or, if you don't want the subject to appear at the precise location indicated by the focusing area markings, use the focus-lock technique described in the next section. |
Using autofocus correctly
When you take a picture, you must press the shutter button a certain way, or the autofocus mechanism can't do its job correctly. After framing the shot, use this two-step approach to lock in the focus:
1. Press and hold the shutter button halfway down.
This step kicks the autofocus mechanism into gear. You usually hear a little whirring or buzzing sound as the camera works to establish the focus point. Some cameras also send out an infrared light beam from the front of the camera to measure the subject distance.
If the camera sets the focus successfully, it signals you via an indicator light near the viewfinder (refer to Figure 1) or by sounding a beep, or both.
2. After the focus indicator signal is given, press the shutter button the rest of the way down.
 | Remember that your subject must be within the camera's focusing area in order to be captured in sharp focus. If you want to compose the picture so that the subject is located at some other position in the frame, do this variation on the two-step shutter dance: |
1. Frame the scene so that your subject is within the focus area.
2. Press and hold the shutter button halfway down to focus on the subject.
3. Reframe the shot to the composition you want.
4. Press the shutter button the rest of the way down.
The camera uses the original focus point you set in Step 2.
| If you're working in autoexposure mode, exposure is also set when you press the shutter button halfway down. |
Solving autofocus problems
You can rely on your camera's autofocus capabilities for most pictures. However, some things can confound autofocus mechanisms.
If you're taking pictures at the zoo and try to photograph a caged or fenced animal, the camera may instead focus on the bars of the cage or the links in the fence. Autofocusing sometimes also goes awry when you shoot highly reflective objects.
In these situations, the following techniques may solve the problem:
- Switch to manual focus, if your camera offers that option.
- If you're working in multi-spot focus mode, switch to center-spot or adjustable center-spot mode. (Again, not all cameras offer these options.)
- If the lighting is dim, add more light. Most cameras have trouble focusing in low lighting because they can't "see" well enough to measure the subject-to-camera distance.
- When a picture is extremely blurry, you may have forgotten to set the correct focus mode.
- For minor blurriness, the problem may not be related to focusing at all. Instead, you may be moving the camera slightly when you take the picture, or your subject may have moved.
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