What does the camera's exposure value mean?

In photography, exposure value (EV) represents all camera aperture shutter combinations that can give the same exposure. This concept was developed in Germany in 1950s, which tried to simplify the process of choosing between equivalent shooting parameters. Exposure value can also represent a step difference on the exposure scale, and 1EV corresponds to twice the exposure ratio, which is usually called "first gear". Exposure value was first represented by symbols. This usage continues to be used in ISO standards, but the abbreviation EV is more common in other places.

The lower the shutter speed, the larger the aperture, and the larger the light passing time and area, that is, the larger the exposure value. In exposure, it is usually represented by the combination of shutter speed (t) and aperture value (f). For the sake of simplicity, it used to be expressed by light value (LV), but now it is uniformly expressed by Exposure Value (EV). EV is the abbreviation of English Exposure Values, and it is a quantity that reflects the degree of exposure. Initially defined as: when the sensitivity is ISO 100, the aperture coefficient is F 1, and the exposure time is 1 s, the exposure is defined as 0, the exposure is reduced by one step (the shutter time is halved or the aperture is reduced by one step), and the EV value is increased by 1.