Eye AF

Eye AF, short for eye autofocus, is a camera feature. It finds a subject's eye in the frame and drives focus there automatically. Once the eye is detected, the camera keeps focus locked on it, even as the subject or camera moves. The feature first appeared in mirrorless cameras for human subjects, and many models now detect animal and bird eyes as well.

Most mirrorless cameras released since around 2018 include some form of eye detection, including models from Sony, Canon, Nikon, Fujifilm, OM System, and Panasonic. Some late DSLR models offer it in live view. Smartphones take a similar approach: their camera apps detect faces and eyes and focus on them automatically. Entry-level cameras usually detect human eyes, while newer or higher-end bodies add animal, bird, and vehicle detection.

Many cameras now include animal and bird detection alongside human eye detection. Animal modes cover dogs, cats, and similar mammals, and bird modes handle perched and flying birds. Detection works best when the eye is visible and large enough in the frame. Wildlife photographers rely on these modes because a small, dark eye surrounded by fur or feathers is hard to focus on by hand.

Face detection finds a whole face and focuses somewhere on it, usually near its center. Eye AF goes a step further and targets the eye itself. The difference matters at shallow depth of field, where the zone of sharp focus can be thinner than the distance between the eye and the nose. With face detection alone, focus can land on the nose or cheek and leave the eye soft.

Continuous autofocus (AF-C) suits Eye AF best because it keeps adjusting focus as the subject moves, which is when eye tracking earns its keep. Single autofocus (AF-S) locks focus once when the shutter button is half-pressed, so it works for a posed subject holding still. For children, pets, wildlife, and events, AF-C with eye detection produces more sharp frames.

Viewers look at the eyes first. When the nearest eye is sharp, the whole portrait reads as in focus, even when the ears, hair, and background blur away. When the eye is soft, the photo feels missed no matter how sharp the rest of the frame is. This is why portrait photographers have always focused on the nearest eye, whether by hand or with Eye AF.

Most cameras step down gracefully. When no eye is detected, the system looks for a face, then a head or body, and focuses on the best match. When the subject turns back toward the camera, eye detection picks up again. If detection keeps failing, switching to a single focus point placed over the eye is the reliable fallback.

Usually, though with limits. Clear glasses rarely block detection, but strong reflections on the lenses can make the camera focus on the glare instead of the eye. Sunglasses hide the eye, so most cameras fall back to face or head detection. Hats and hair covering part of the face reduce accuracy. A check at playback zoom shows whether focus landed where it should.

Eye detection needs enough light and contrast to recognize an eye, so performance drops in dim scenes. Cameras vary widely: newer bodies with subject-detection processors keep finding eyes at light levels where older models give up. When detection becomes unreliable in low light, a single focus point over the eye, or focusing on a brighter edge at the same distance, works better.

On most cameras, yes. The camera picks the nearest or most visible eye by default, and a button, joystick, or touchscreen tap switches to the other eye. Some models save the choice as left, right, or auto. Switching matters when a subject's head is turned and the camera picks the far eye, which would leave the near side of the face soft.