What is exposure?

Photographic exposure refers to the photographer accurately judging the light state of the shooting environment, and then adjusting the combination of shutter and aperture to expose the silver salt and record the light. If explained scientifically, it is: the intensity of light multiplied by the time of light action. The "light intensity" in the definition refers to the intensity of light shining on the photosensitive film, that is, illuminance; In the definition, "the time of light action" refers to the time when the photosensitive film is irradiated by light, that is, the exposure time. The exposure is expressed as e, and the calculation unit is lux seconds. To obtain a certain exposure, the greater the light intensity, the shorter the exposure time; The smaller the light intensity, the longer the exposure time. Exposure is one of the most basic and important techniques in photography. High quality images must be based on accurate exposure. The principle of exposure is easy to understand, but mastering exposure technology requires the combination of practice and theory and the long-term efforts of photographers.