What is the relationship between metering and focusing when taking a SLR photo?

Just press the shutter for average metering.

The step of spot side metering is that the original metering of the low-end camera is in the middle area. You use this area to measure where you want to measure, such as the face, and then lock this sidelight value.

Focus separation means that metering and focusing are set to different buttons by the camera's self-defined function from the half shutter, and their respective functions are completely separated. After I separate, the half shutter is set to metering, and the exposure lock key is used for focusing. The whole use process is divided into three steps:

1. Focus on the part to be measured (such as human face) with the center, and measure the light by half pressing the shutter (keep half pressing before fully pressing the shutter) →2. Use the exposure lock key to focus the focused part after re-composition →3. Press the shutter completely to shoot. The whole process is one step less than using the exposure lock key, which is also the fastest photometry shooting method, which can make people better understand the concept of exposure. The second method is extended from 20 days to 60 days.