Use single autofocus for a subject that stays still and continuous autofocus for one that moves. Then choose a focus area that tells the camera where to look. These are separate decisions, and understanding the difference makes menus much easier.
What the autofocus names mean
| Behavior | Common labels | Starting use |
|---|---|---|
| Focus once, then hold | AF-S, One-Shot AF | A stationary object |
| Keep adjusting while activated | AF-C, Servo AF | People moving, pets, action |
| Let the camera switch behavior | AF-A, AI Focus on some models | Casual mixed subjects |
| Turn the focus ring yourself | MF | Repeatable setups or difficult targets |
Names and availability vary by brand. AF-S printed on a Nikon lens barrel also has a separate meaning relating to its motor; here we mean the camera’s focus mode.
Focus area and subject detection do different jobs
A single-point area lets you place a small target precisely. A zone gives the camera a larger region to work within. A broad area lets it search more of the frame.
Subject detection helps it identify a person, eye, animal or other supported subject inside the available search area. Selecting the correct subject type can help, but the camera still needs to see something it can recognize.
Start broad enough to follow the subject. Narrow the area if the camera repeatedly chooses a foreground obstacle or the wrong person.
Set up focus for a person or pet
- Select continuous AF.
- Enable the appropriate subject or eye detection if your camera offers it.
- Choose a zone or tracking area that you can keep on the subject.
- Activate focus before the moment happens, rather than pressing everything at once.
- Review a frame at high magnification and check the intended eye.
If a runner’s face is sharp but their hands blur, focus may already be working correctly. You may need a faster shutter speed instead. See how to diagnose blurry photographs.
Focus through an obstacle
At a zoo fence or a window, a broad area can select the nearer surface. Try a smaller focus point on the subject, change your position and look for a clearer line of sight. If the camera still hunts, manual focus with a magnified view can be more predictable.
For a stationary tabletop subject, single AF or manual focus also prevents a last-second change to the wrong object.
Should you use back-button focus?
Back-button focus assigns focusing to a separate control such as AF-ON. It can be useful when you want to stop refocusing without lifting your finger from the shutter. It is optional, and takes practice.
Before enabling it, learn which button now starts focus and whether the shutter button still does. A missed setting can look like a broken lens. Practice on an unimportant scene before using it for an event.
Technical references
Nikon School’s autofocus guide explains focus behavior and area choices. Nikon’s AF-ON guide explains separating focus from the shutter release.
Frequently asked questions
What is the difference between AF-S and AF-C?
AF-S acquires focus and normally locks while the focusing control stays engaged. AF-C keeps adjusting while focus is activated, making it a better starting point for movement.
Is eye detection a focus mode?
Eye detection identifies a target. Single or continuous AF controls when the camera adjusts focus. Available combinations depend on the camera.
Should I use continuous autofocus for portraits?
We recommend continuous AF with eye detection when a person may sway or move. Single AF remains useful for a still subject when you want focus to stay fixed.