What is the meaning of af-on behind Canon camera?

The AF-ON button on the back of Canon camera can set one or several designated focus points in the menu. Pressing this button will switch to these focus points. That is, Canon's so-called "registering autofocus point" function.

Function overview: Assign the manually selected autofocus point to the AF-ON button or the automatic exposure lock button, so that you can switch to the specified autofocus point with one-button operation and automatically measure and focus.

On Canon and Nikon models, the AF-ON key also has an exposure lock function. Usually, when shooting, you can lock the exposure parameters by pressing this * key, that is, the zoom-out key. This exposure lock will be released by pressing the shutter once after shooting, or it will be released about 5 seconds after pressing it.

Press the exposure lock again when shooting next time, but if AF-0N is set to automatic exposure lock (hold), once the AF-ON key is pressed when shooting, the exposure parameters will be locked all the time. No matter how many photos you take and how long it takes, the exposure parameters will not change until you press the AF-ON key again.

Extended data

Camera shutter key: mainly used for shooting. Half of this button is used to start autofocus, and all buttons are used to take pictures. Power supply/screen light switch: the switch control of the camera's main power supply is very useful when setting the light bulb icon to turn on the screen background light and adjusting the parameter settings in poor light environment.

Exposure mode selection key: press and hold this key, and after dialing the function wheel, you can switch different exposure modes, including: aperture priority, S-speed priority, P-program exposure and M-manual exposure. This function key is only available in Nikon mid-range and high-end machines, and it is realized in entry-level low-end machines through the function mode dial in the right shoulder position.