What is the ev value of the camera?

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".

Extended data:

Every time the exposure value increases 1, the exposure will change by one step, that is, the exposure will be halved, for example, the exposure time or aperture area will be halved. This may cause confusion. The reason for the decrease, rather than the increase, is that the exposure value reflects the setting of camera shooting parameters, rather than the illumination of the film (mentioned in the next paragraph). The increase of exposure value corresponds to a faster shutter speed and a larger F value. Therefore, a bright environment or a higher sensitivity (commonly known as ISO) should correspond to a larger exposure value.

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