Focus Points Quiz – Master Autofocus Point Selection

With automatic point selection, the camera picks what to focus on, usually the closest object or whatever has the most contrast. That may not be the subject you intended, such as a branch in front of a face. Choosing the focus point yourself avoids this.

Single-point AF focuses on exactly the spot you place the point on. That precision suits still or slow subjects, such as a portrait's eye or a detail in a landscape. Fast, erratic subjects are better served by zone or tracking modes.

AF-S focuses once when you half-press the shutter and then locks, which suits still subjects. AF-C keeps refocusing as long as you hold the button, tracking a subject that moves toward or away from you. Both work for still photos.

Viewers look at the eyes first, so they must be sharp. Focus on the eye nearest the camera because it is the most prominent, and at wide apertures the farther eye may fall slightly soft. A sharp nose or forehead with soft eyes looks like a missed focus.

Back button focus moves autofocus from the shutter button to a button on the back of the camera. You focus with your thumb and take pictures with your index finger. That lets you lock focus and shoot repeatedly without refocusing, or keep tracking a subject, without switching modes.

Focus and recompose means locking focus with the center point, then turning the camera to frame the shot. Turning the camera swings the plane of focus, so the subject can end up slightly out of it. At wide apertures with very shallow depth of field, that small shift can leave the eyes soft.

Eye-detection autofocus finds a person's or animal's eye in the frame and keeps focus on it, even as they move. Since the eye is the most important point of focus in a portrait, this removes much of the work of placing a focus point. It makes sharp eyes far more reliable at wide apertures.

A single point is precise but hard to keep on a subject that moves unpredictably, like a bird or an athlete. Zone or group AF uses a cluster of points, so the camera can still hold focus if the subject drifts off one point. Still subjects are better served by single-point precision.

A linear focus point detects contrast in one direction only, so it can miss a line that runs the same way as the sensor. A cross-type point reads contrast both horizontally and vertically, so it can lock onto almost any detail. That makes it more reliable on a wider range of subjects.

Trap focus means setting focus on a spot where you expect the subject to arrive. When the subject enters that zone and becomes sharp, the camera fires. It is useful for birds landing on a perch or athletes crossing a known point.