Aperture is one of the parameters of cameras, which is extremely important in dimly lit places. In optical devices, it is the diameter of the aperture limited by the aperture through which light enters. Aperture increases with the diameter of the aperture, and decreases with its length. The larger the aperture of the system, the more sensitive the device.

If in the specification the camera has an aperture of F1.0, it means that 100% of the light enters the lens and the resulting image from the camera is characterized by high sharpness and better illumination, a common parameter in cameras with color mode at night.

P - the object, P' - its image, Pl. front. - plane in which the object is located, Prz - input aperture, Źr - input pupil, Ob - lens, u - aperture angle (source wikipedia)

Aperture number

f/1

f/1.4

f/2

f/2.8

f/4

f/5.6

f/8

f/11

f/16

f/22

f/32

f/45

f/64

f/90

f/128

...

The F1.0 aperture value means that the focal length of the lens is equal to the diameter of the aperture. Each subsequent position indicates an aperture setting at which twice as much light is let into the lens. In addition, the lowest aperture value for a given lens is commonly referred to as the lens brightness, although it is actually the inverse of the root of the lens brightness. This lowest aperture value can be an intermediate value, such as f/1.8, f/3.5, f/4.5, and is dependent on the design of the lens itself.

 

The table below shows the amount of light transmitted at different apertures. If the aperture of the lens allows it to close completely, the F-number is equal to infinity (this can be denoted by the term closed - closed). Most often two values of the F-number are given, the first of which specifies the maximum opening of the aperture, and the second - the minimum.

F-number	The amount of light transmitted
1.0	100%
1.4	50%
2.0	25%
2.8	12.5%
4.0	6.3%
5.6	3.31%
8.0	1.6%
11	0.8%