Learn how to get perfect focus every time. By combining your knowledge of autofocus points and modes, you’ll be able to ensure that all your shots are sharp with minimal effort.
Most DSLR systems autofocus using a system known as Passive autofocus, which determines the distance to the subject by computer analysis of the image. This is an extremely sophisticated system and most pro photographers will happily rely on autofocus because of its accuracy.
Most people think that focusing is a simple enough procedure – just half press the shutter button and wait for the focusing points to light up. But to get really accurate focusing for all photographic situations, you need to know and understand the focusing system in more detail.