How do I choose between single-shot and continuous autofocus?

The key question is whether the subject is likely to move before you take the picture. Single-shot autofocus acquires focus and then holds that focus, which is useful for a stationary subject. Continuous autofocus keeps adjusting focus while active, which is useful when the subject is moving or may move. On Canon’s EOS Rebel T7, for example, Canon describes One-Shot AF as locking focus while the shutter button is held halfway, and AI Servo AF as continuously adjusting focus under that condition. Those are model-specific names and instructions, not universal labels. [S1]

A simple starting rule: still subject, try single-shot; moving or unpredictable subject, try continuous. Then check whether the camera keeps focus where you expect.

Decide based on the moment you want to capture. If the person is standing still for a posed picture, single-shot can be a straightforward choice. If they are walking, turning, or likely to move between focusing and taking the picture, continuous autofocus is the better starting point because it keeps adjusting while active.

For a practical test, take a few pictures in a low-pressure setting: one while the person is still and another as they move. Keep the distance and framing similar, and compare whether the intended subject looks in focus. This helps you learn how your own camera behaves; it does not guarantee every frame will be sharp. Also check whether focus remains active in the way you expect when you press the shutter, since controls and settings differ.

Treat those words as descriptions of behavior, not guaranteed menu labels. Manufacturers can use different names, and available options can differ between camera models. Canon’s EOS Rebel T7 calls its stationary-subject mode One-Shot AF and its moving-subject mode AI Servo AF; it also describes AI Focus AF as able to switch from One-Shot to AI Servo if a stationary subject starts moving. [S1] On the EOS M50, Canon describes Servo AF as continuous focusing for moving subjects. [S2]

Look in your specific camera’s manual or menu guide for autofocus options, and confirm what each does on your model. These examples do not establish that another camera has the same labels, switching behavior, or tracking capabilities.

Use this short process:

1. Ask whether the subject is still, moving, or likely to move before the picture.
2. For a still subject, try the camera’s single-shot-style option; for a moving subject, try its continuous-style option.
3. Find the exact mode names in your camera manual. Confirm how focus starts, whether it continues adjusting, and how your camera behaves when you take the picture.
4. Test the choice on a few representative shots and review focus on the intended subject.

For example, if you are photographing a stationary mug, start with the single-shot-style mode. If you are photographing someone walking toward you, start with continuous autofocus, then verify that your model’s mode is designed to keep adjusting as the person moves. Focus tracking around the frame is a separate capability from simply adjusting focus as subject distance changes; Canon makes that distinction in its EOS M50 explanation. [S2] Your manual is the guide to what your camera supports.