In photography, what is photometry and how to measure it correctly?

First of all, you asked the wrong question. As long as the camera is not broken, all metering must be correct. The photometric element obtains a physical value according to the incident light, and there is no right or wrong.

Second, if you only rely on the value given by photometry for exposure, you will only get a photo that meets the gray level standard of 18%, not the one you want.

Third, between photometry and exposure, it is necessary to manually correct to get the desired photos. The correction amount can be forward correction (+exposure) or reverse correction (-exposure). What you need to know is when you need+exposure and when you need-exposure.

Fourthly, the means to realize the correction are: a) semi-automatic adjustment of EV based on photometry through exposure compensation function; B) Use M-gear to directly control the exposure, and manually adjust the exposure, completely manually.

5. How to calculate the exposure correction? Remember a rule: when the background is bright+exposure, when the background is dark-exposure, that is, it changes inversely with the background brightness. How much should I increase or decrease? It is related to the brightness difference between the background and the subject. The greater the brightness difference, the greater the addition and subtraction. Observe the photos through the camera LCD screen, and if there are too many, adjust them back a little.