Digital Compact Cameras
Unlike single lens reflex cameras (SLR), digital compact cameras do not come with an option to change the lenses. Instead, focus adjustment for digital compact cameras must be done using a series of switches and image recomposing. First, you must make sure that the camera's preset function settings are correct for the conditions under which you are shooting. For example, the camera's macro setting allows for closer focusing conditions than the landscape photography setting. Then you should compose your photo so that the desired plane of focus is in the exact center of the photograph (most cameras focus on what is in the center of the viewfinder). Then depress your shutter only halfway. This will lock the focus into place. Hold the shutter in this position and recompose your photo. Finally, finish pressing the shutter release to take the photo.
Digital SLR Cameras
Most digital SLR cameras are designed with a matrix focus that automatically adjusts the camera for the subject that is nearest to the screen. If this is not the desired subject for your photo, you can adjust the focus using the auto-focus locking mechanism. First, determine if you are using pre-set camera settings, such as macro or portrait modes. Set your camera to the correct mode, or choose the manual override setting to maintain control of the aperture setting and shutter speed. Then locate the auto-focus lock button on your camera. Some cameras maintain a separate auto-focus locking button, which may be near the lens, or on the lens itself. For other cameras, this button is built into the shutter release, and is engaged by pressing the shutter release button halfway down. Using this method, compose your photo so that the desired focal plane is in the center and closest to you. Then engage the auto-focus lock and recompose your photo before taking the picture. Alternately, you can turn off the camera's auto-focus feature by switching both the lens and camera settings to manual focus mode. Then, focus the camera by turning a ring on the lens itself. When the subject appears clear through the viewfinder of the lens, it is safe to take the photo.