How Autofocus Cameras Work

By: Gary Brown

Focus Lock: The Key to Great Autofocus Pictures

The camera user can often fool the autofocus system. A pose of two people centered in the picture may be unclear if the focus area (the area between the two square brackets) is in the middle of the two people. Why? The camera's autofocus system actually focuses on the landscape in the background, which is what it "sees" between the two people.

The solution is to move your subjects off-center and use the focus-lock feature of your camera. Typically, focus lock works by depressing the shutter button part-way and holding it while you compose the picture. The steps are:


  1. Compose the picture so that the subject is either in the left third or the right third of the picture. (This makes for pleasing pictures.) You will come back to this position.
  1. Move the camera right or left so the square brackets in the center of the viewfinder are over the actual subject.
  1. Press and hold the shutter button halfway down so the camera focuses on the subject. Keep your finger on the button.
  2. Slowly move your camera back to where you composed the picture in step 1. Press (squeeze) the shutter button all the way down. It may take some practice to do it right, but the results will be great!

You may also use the above procedure in the vertical direction, say when taking a picture with mountains or the shore in the background.