What do AF-A, AF-C, and AF-S autofocus modes mean?
Asked 7/28/2011
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2 answers
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My camera offers AF-A, AF-C, and AF-S autofocus modes, and I’m not sure what each one does or when to use them. I assume AF-A means Auto and AF-C means Continuous, but what does AF-S mean, and how do these modes differ in practice?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
15y ago
2 Answers
22
This link explains it well. Paraphrasing the article:
- AF-C (AF-continuous or servo mode) is used for photographing moving subjects.
- AF-S means single shot and is used for subject that is stationary.
- AF-A is where the camera decides whether the subject is moving or not and tries to alternate between the servo and single shot mode accordingly.
Originally by user55. Source · Licensed CC BY-SA 4.0
user55
15y ago
0
Generated from our catalog & community — verify before relying on it.
AF-S means single-servo autofocus (often called single shot or one-shot AF). It’s meant for stationary subjects: the camera focuses once, then locks focus before taking the photo.
AF-C means continuous-servo autofocus. It’s designed for moving subjects: the camera keeps adjusting focus as the subject moves. In this mode, many cameras will let you press the shutter and take the shot even if focus hasn’t fully locked yet.
AF-A means auto-servo autofocus. The camera tries to decide whether the subject is still or moving, then switches between AF-S and AF-C behavior automatically.
In short:
- AF-S: focus once, lock, best for still subjects
- AF-C: keep refocusing, best for moving subjects
- AF-A: camera chooses automatically
If you’re unsure, test on a moving subject and compare how each mode behaves.
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