To set the desired AF setting, switch to AF, select the desired shooting mode (AF will operate only in the automatic and semi-automatic modes) and press the AF button on the camera. Hold the AF-ON button until the camera achieves focus – when autofocus is achieved, the AF point will turn green if you're using One-Shot AF mode or blue in Servo AF mode.
Canon autofocus systems are so easy to use and so effective that many photographers rarely switch to Manual Focus or MF (not to be confused with Manual exposure mode, denoted by M in the camera menu and on the mode dial, if your camera has one). But how do they work, and what do the different options mean?
When you use autofocus, there are a range of settings and options available, which may vary from camera to camera. For easier menu navigation and setting, all the AF settings and Custom Functions are grouped into one menu tab, so there is no need to jump into different menu areas to make changes. For example, these are some of the main choices available in the EOS R5 Mark II:
AF operation: One Shot AF (for still subjects), Servo AF (for moving subjects), or AI Focus AF mode, in which the camera chooses which of these two to use, according to the subject movement it detects. Find out more about AF operation modes.
AF Area (or AF Method on some cameras):
1-point AF – the camera focuses using a single AF point;
Spot AF – the camera focuses using an even smaller area than 1-point AF;
Expand AF area – there are two options here. With either, the camera focuses using a single AF point, but if it is unsure then it uses another AF point to assist, or may switch to that point instead – either the next point horizontally and vertically, or the next point diagonally. These are effective with moving subjects, which are difficult to track with 1-point AF;
Flexible Zone AF – uses auto selection AF within a larger area, optionally focusing on the nearest subject or using various criteria such as faces, subject motion and subject distance.
Whole area AF – uses a much wider area for autofocus (up to 100% horizontal and 100% vertical coverage, depending on the lens). As well as using subject distance and face tracking, the latest cameras offer animal and vehicle tracking. On some cameras, this appears as a separate Subject tracking menu option.
Find out more about AF methods.
Subject to detect – on the latest cameras with Intelligent AF, this instructs the camera to give priority to People, Animals, Vehicles or No Priority. On some cameras, a separate Subject tracking option must be enabled first. Find out more about AF configuration options.
Eye Detection on or off, plus on some cameras the ability to prioritise the subject’s left eye or right eye.
Register People Priority – Up to 100 people can be pre-registered on cameras that have this capability, and then the top 10 can be prioritised in order of importance. The camera will then automatically attempt to detect and track those faces in a scene.
Action Priority – once this is enabled, you can select a sport event – soccer, basketball or volleyball – and the camera will track specific actions that are typically seen in this type of game, without any intervention from the photographer.
Touch & drag AF settings (available on selected newer cameras including EOS R System models) – see the section below about specifying the AF point.
Movie Servo AF – Set the camera to keep focusing on the subject while you’re recording video. If you’ve specified a subject to detect, you have the option to activate Detect only, in which case Movie Servo AF stops if it is unable to detect the subject you’ve specified. This can be useful if someone walks out of a shot, as it will prevent the camera from refocusing on the background. This feature is common to Canon's cinema cameras.