What are the three elements of aperture, shutter and iso?

Aperture represents the size of the effective light entrance hole of the camera lens, expressed by F value. The larger the value, the smaller the light entrance hole, and it increases with root number 2 as a proportional sequence, because the aperture value is defined as It is inversely proportional to the diameter of the light hole, so every increase of 2 times the value means that the area of ??the light hole is reduced by half.

The shutter represents the exposure time of the photosensitive element. Under normal circumstances, it is expressed as the reciprocal of the exposure time, and increases in a proportional sequence of 2. The larger the value, the shorter the exposure time.

ISO means that there is no direct connection between the sensitivity and the aperture and shutter speed. If the sensitivity (iso) is high, the color of the photo will be relatively bright (this is the intuitive feeling when looking at the photo). If the iso is low, the color of the photo will be relatively dark.

The gear design of the aperture

The value of the two adjacent gears differs by 1.4 times (the approximate value of the square root of 2 1.414). Between the two adjacent gears, the diameter of the light transmission hole The difference is 2 times the square root, the area of ??the light-transmitting hole is doubled, the brightness of the image formed on the film is doubled, and the time required to maintain the same exposure is doubled.

It is worth mentioning here that the smaller the aperture F value, the larger the clear aperture, the more light that enters in the same unit of time, and the amount of light that enters the upper level is exactly the same as that of the next level. double. For example, if the aperture is adjusted from F8 to F5.6, the amount of light entering will double. We also say that the aperture is opened one step wider.