Shooting a frame-filling close-up of a toddler eating spaghetti doesn’t usually pose much of a technical problem for the autofocus (AF) and autoexposure (AE) systems built into today’s compact digital cameras–they’ll focus on her face and generally give you an excellent exposure. But when you place that toddler’s face off-center near the edge of the frame, compose a double portrait of mom and dad, or photograph a group of people sitting around the dinner table, things start getting interesting.

Conventional AF systems, even those with multiple AF zones, will sometimes miss the faces and focus on something else that’s between them, farther away, or closer. The result: The people in your picture will be out of focus, blurry, and over- or underexposed–not a good thing.

Sure, you can use your brain, lock focus on your intended subject by holding in the shutter button partway, recomposing, and shooting. But in the excitement of the moment, it’s easy to forget. And even though it only takes a moment to autofocus the intelligent way, in that brief instant little Rachel’s perfect expression can well have vanished.

Fortunately, a number of leading camera manufacturers have addressed this sticky problem literally head-on, and have come up with ingenious solutions known as Face Recognition, Face Detection, or Face Priority Mode.

No face detection systems can perform miracles of course, such as simultaneously achieving a sharp, perfectly exposed image of uncle Fred who is 27 feet away and cousin Charlie whose face is three feet from the camera. However, based on my hands-on experience with Fujifilm. Canon and Nikon cameras incorporating face recognition systems, they do a remarkably good job well over 90 percent of the time, and they have the great advantage of doing so automatically without time-consuming user intervention.