Ask for advice, how to choose the focus mode for 80d?

First, single-point aiming: single-point autofocus (manual selection)

Establish focus at a point.

This mode allows you to focus with a single manually selected autofocus point. All autofocus points are unavailable except the selected autofocus point. Single-point autofocus mode has excellent focusing accuracy. It can be used for various subjects and scenes with less subject movements, such as landscapes, portraits, still life photos, etc.

Second, area aiming: area autofocus (manual area selection)

Shooting an object using multiple autofocus points

In this mode, you can select one of the nine focus areas, each of which consists of multiple autofocus points. This mode is suitable for some action subjects, such as portraits of moving objects, street shooting and so on.

Third, area aiming: large area autofocus (manual area selection)

Capture the theme in a wide range. This mode divides the picture into three areas (left, middle and right), and each area uses multiple autofocus points for focusing. Compared with area autofocus, large area autofocus is more suitable for subjects with more intense movement. Auto-focus points can be automatically selected in the area, and the number of auto-focus points used will vary according to the subject's situation.

Fourth, regional aiming: 45-point autofocus.

Auto-select autofocus point: In this mode, this function will automatically select autofocus point according to the position and size of the subject. All 45 autofocus points can be selected, but the available number will change with the distance between the subject and the camera. As in other modes, this function detects skin color when the autofocus mode is selected at 45 o'clock. It is also suitable for portrait photography.