What value is the exposure meter used to measure?

An exposure meter is used to measure the intensity of light.

The related configuration files of the exposure meter are as follows:

In photography, the exposure meter is used to determine the appropriate exposure time. When the film sensitivity and shutter speed are known, the exposure meter gives the aperture value to obtain the best exposure. Exposure meter is also used to control the brightness of lighting, or as a handheld instrument to ensure that the light intensity meets the requirements of shooting.

In photography, there are many kinds of exposure meters, which are mainly divided into exposure meters and color temperature meters according to their different functions and uses. Among them, the exposure meters in exposure value are divided into incident exposure meters, reflection exposure meters and mixed exposure meters according to different measurement methods. According to photometric elements, the most common exposure meters are selenium, cadmium sulfide and silicon.

The exposure meter made of selenium and silicon uses a probe with photoelectric effect. The voltage generated by these probes is proportional to the light intensity. The voltage generated by the selenium probe is enough to drive a pointer. The silicon probe needs an amplifier circuit and a power supply (such as a battery) to work.

The principle of cadmium sulfide probe is photoresistance, and it also needs a power supply. Modern exposure meters generally use silicon probes or cadmium sulfide probes. The measured data can be displayed by ammeter or LCD.

Many modern consumer cameras and camcorders contain exposure meters integrated into machines, and all these metering methods are based on the principle of reflective exposure meters. They can measure the light intensity in the photo format to automatically select the appropriate exposure constant.