What is the most important factor to control camera exposure? How does it work?

The most important factors are aperture size, shutter speed and their combination.

Now the aperture value of the lens mark:

f/ 1、f/ 1.4、f/2、f/2.8、f/4、f/5.6、f/8、f/ 1、f/ 16、f/22、f/32、f/45、f/64

Each numerical value is positively correlated with the adjacent numerical values, indicating that the luminous flux of the latter numerical value is half that of the previous numerical value, and the luminous flux of the previous numerical value is twice that of the latter numerical value. Because according to the calculation formula of circular area, the amount of light passed by the lens is inversely proportional to the square of f coefficient.

The concept of "relative aperture" is adopted in order to calculate the exposure in actual photography and measure the actual effect of aperture apertures of different lenses with a unified standard.

Relative aperture = [lens focal length]/[entrance pupil diameter] = f/d

For example, if the focal length of the lens is 50mm and the diameter of the entrance pupil is 25mm, the relative aperture of the lens is 50/25=2. )

For example, the luminous flux of f/5.6 is half that of f/4; Twice as much as f/8.

Ordinary shutter

Eight seconds, four seconds, two seconds. 1 sec,1/2s,1/4s,1/8s,1/5s,1/30s,/kloc-0.

The shutter speed of 1/30 seconds is twice that of 1/60 seconds.

When the shutter speed is constant, the exposure will double with a larger aperture.

When the aperture is constant, the exposure will be reduced by half if the shutter speed is increased by one step.

For example, when the aperture value is set to f4 and the shutter speed is 1/500 seconds, the exposure effect is the same as when the aperture value is f5.6 and the shutter speed is 1/250 seconds.

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