What are the specific ISO functions of the camera?

ISO sensitivity is an international unified index to measure the photosensitive speed standard of film used in traditional cameras, which reflects the photosensitive speed of film (actually, the photochemical reaction speed of silver and light).

Traditional cameras can choose low-speed, medium-speed or high-speed films with different ISO sensitivities according to the specific conditions of shooting scenes. In traditional film cameras, ISO stands for the standard of photosensitive speed; In digital cameras, the definition of ISO is the same as that of film, representing the photosensitive speed of CCD or CMOS photosensitive elements. The higher the ISO value, the stronger the photosensitivity of photosensitive materials.

The calculation formula of ISO is S=0.8/H(S sensitivity, h is exposure). As can be seen from the formula, the higher the sensitivity, the lower the requirements for exposure.

Extended data:

About the setting of sensitivity: For landscape photography, the sensitivity can be minimized, even if the light is dim, there is no need to improve the sensitivity, because the tripod can solve the problem of slow photography.

Commercial photographers mainly work in the studio, they mainly use big flash, there is no need to improve ISO. The shooting environment of news documentary photographers is the most complicated, and any kind of lighting may be encountered. Therefore, we must adhere to the principle of "taking pictures first" and sacrifice the image quality to get valuable pictures. Large aperture and ISO6400 are usually used.

Setting principle of sensitivity: try to use the lowest value under the premise of ensuring that the picture is not empty.

Baidu Encyclopedia-ISO in Digital Camera