Autofocus takes care of one of the most fundamental aspects of photography for you, but understanding how AF works can help you know which mode to choose, and when best to use it
When you half-press your camera’s shutter release button, it focuses automatically on the subject you’re photographing. This happens so quickly you probably take it for granted, but stopping to think about the behavior of your camera’s autofocus (AF) system is key to using it properly and creatively.
The first thing to realize about autofocus is that it can work in one of two modes: single or continuous. This is independent of choosing the focus area in the frame. You can switch between these (or into manual focus mode) using either a lever on the front of your camera, or options on the touchscreen.
Let’s have a look at how the two modes differ from one other, and when you might use one instead of the other.
Single AF
When your camera is in single AF mode (also known as AF-S), it focuses on a subject when you half-press the shutter release button and locks the focus at that distance until you either completely press this button or release it. If your subject changes position after you’ve locked on it, you might want to let go and half-press again to ensure it’s properly sharp.
The big reason single AF mode is so popular is that it lets you focus easily on subjects that are not in the middle of the frame or under the focus points that are currently selected. After locking focus by half-pressing the shutter release button, you can recompose the image knowing the camera will not change this focus when you fully squeeze the shutter release and make the picture.
© Bryan Minear
Focus > lock > recompose is only one way of photographing off-center subjects (others include moving the active focus point and focusing manually), but it is arguably the fastest to use and the most intuitive – once you’ve had time to practice.
Another advantage of AF-S mode is that the camera won’t create a picture until the subject is locked in focus – unless you tell it not to via the AF/MF SETTING menu. Only making a picture when the focus is locked reduces the chance of getting an out-of-focus image by accident – at least when photographing non-moving subjects.
AF-S is a great mode for portraits, landscapes, still life, and any other subject that doesn’t move.
Continuous AF
As the name implies, continuous AF (or AF-C) focuses non-stop while the shutter button is half-pressed, readjusting to match the distance of the subject in front of the camera. It’s most useful when you’re photographing moving subjects – from athletes running on the football field to kids playing on the beach. Your camera will adjust focus to keep the moving subject looking sharp.
© Katie Orlinsky
Obviously, you can’t use the focus > lock > recompose method for off-center compositions (as soon as you recompose, the camera will simply re-focus on whatever is now at the AF spot), but AF-C is the mode to turn to when your subject is on the move.
Manual Focus
The third focusing mode is manual (or simply M). You can use this for any kind of photography, but it can take time to focus manually, which may result in you missing the moment. For this reason, we recommend using AF-S or AF-C in most cases. That said, manual focusing can be useful when:
- You’re photographing at night.
- You’re photographing still-life compositions.
- You want to take precise control over where you are focusing in a scene.
© Alison Conklin
Your Next Steps
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- CHALLENGE Switch to AF-C mode and make some pictures of moving subjects. Post the results to social media with the hash tag #MyFujifilmLegacy, and tell us about what you chose to photograph. You can also submit your work here for a chance to be featured on our social media channels.
Header image © Daniel Tengs