What is the function of exposure meter in photography and how to use it?

An exposure meter is used to measure the light of an object. A separate exposure meter, because it can be held by hand, is more convenient and can be measured near the model's face. This metering method measures the incident light, which is a little different from the reflected light of the camera, but there is no more accurate problem, and the accuracy is the same. The greatest significance of exposure meter lies in the measurement of flash lamp, not the brightness measurement under ordinary modeling lamp. Flash measurement needs to be synchronized with the flash. The exposure meter can measure the accurate flash exposure without actual shooting, and then input the measured parameters into the camera for actual shooting. This is especially useful when shooting with a large format camera, because the cost of a large format film is more than 100 yuan. The most important thing is that filming can't present images in real time. If you shoot hundreds of large frames for an advertisement, and then the model has flown back to France, and the photos are all black after a week, do you think the boss will want to kill you?