CAM · Camera Settings
AF-S vs AF-C: Which Autofocus Mode to Use
One lens, two very different jobs: learn when to lock focus on a still subject and when to let the camera track a moving one.
Diagrams
Autofocus mode answers one question: does the camera keep focusing after it has locked on? AF-S (One-Shot AF on Canon, AF-S on Nikon, Single AF on Sony) focuses once when you half-press the shutter and then holds that distance, confirming with a beep and a green box. It is the right mode for anything that stays still - portraits, landscapes, architecture, product and macro work - and it is the most accurate mode, because the camera can take its time and verify the lock. The trade-off is that if the subject moves after the lock, the frame is soft. A second weakness appears when you focus on a face and then recompose: with an f/1.4 lens at close range that swing can pull the eyes out of focus. Move the AF point instead of recomposing when depth of field is thin.
AF-C (AI Servo on Canon, AF-C on Nikon, Continuous AF on Sony) keeps driving the lens while the shutter is half-pressed, predicting where a moving subject will be at the moment of exposure. That makes it the mode for children, pets, sport, wildlife and anyone walking toward you. Pair it with continuous burst shooting and it will hold focus across the whole sequence. The usual failure is leaving AF-S on the camera for a running child: only the first frame comes out sharp.
Most brands also offer an automatic mode (AF-A or AI Focus) that switches between the two on its own. It guesses wrong at the worst moments, so serious shooters set the mode manually. Two companion settings matter just as much. The AF area mode decides how much of the frame the camera searches: a single point for precision, a wide or zone area for fast-moving subjects, and subject recognition or eye-AF for people and animals. Shutter-release priority decides whether the camera fires before focus is confirmed; set focus priority for portraits and still life, and release priority only for fast sport where keeping the frame rate up matters more.
Many photographers also move focus off the shutter button entirely. With back-button focus, AF-C runs only while the thumb holds the AF-ON button, and a press of the shutter freezes the focus exactly where you left it.
Key points
- AF-S (One-Shot) locks focus once - ideal for still subjects; refocus if the subject moves.
- AF-C (AI Servo) tracks continuously - the mode for children, pets, sport and wildlife, paired with burst shooting.
- Avoid focus-and-recompose at wide apertures; move the AF point instead to keep the eyes sharp.
- Skip the automatic AF-A mode for critical work and choose AF-S or AF-C yourself.
