What is an aperture?
1. Aperture is a part of a camera that controls the aperture of a lens to control the depth of field, the quality of lens imaging, and the amount of light entering in cooperation with the shutter. Sometimes it also represents the concept of aperture value.
2. The size of the expression aperture is expressed by the f value. For the lens that has been made, the diameter of the lens can not be changed at will, but the lens pass can be controlled by adding polygons or circular gratings with variable area. This device is called aperture, aperture f value = focal length / aperture of the lens. The influence of aperture on photos: the larger the aperture, the greater the amount of light, the smaller the depth of field, the smaller the f value.
Types of Aperture:
1. Fixed aperture: the simplest camera has only a fixed aperture with a circular hole.
2. Walter Huser aperture: the original variable aperture was just a series of circular holes of different sizes arranged around a disk with a central axis; rotating the disc moved the appropriate size of the hole to the optical axis to control the aperture. In the middle of the nineteenth century, John Walter Hauser invented this kind of aperture.
3. Cat's eye aperture: a piece of metal sheet with oval or rhomboid hole in the center is divided into two equal parts. Two pieces of metal sheet with semi-oval or semi-rhomboid hole are arranged in pairs, and the cat's eye aperture can be formed by relative movement. Cat eye aperture is often used in simple cameras.
4. Iris aperture: it is composed of a number of overlapping arc thin metal blades, the clutch of the blade can change the size of the central circular aperture. Some cameras can change the aperture of the aperture with the help of the ring on the rotating lens tube, while others use the microprocessor chip to control the micromotor to automatically change the aperture of the aperture. The arc thin metal blade can be up to 18 pieces. The more thin metal blades there are, the closer the aperture is to the circle. The shape of thin metal blade can be designed by computer, and only 7 thin metal blades can be used to obtain the near circular aperture.
5. Instantaneous aperture: the aperture of modern single-mirror reflective camera lens is instantaneous aperture, only at the moment of shutter opening, the aperture is reduced to a predetermined size. The aperture is usually in the largest position.
6. Shutter aperture: some simple camera aperture also has shutter function, called "shutter aperture" this kind of shutter aperture is mostly double blade cat's eye aperture, unlike simple cat's eye aperture is: shutter aperture is usually completely closed. At the moment of pressing the shutter, the double blade aperture opens to a predetermined aperture, keep the aperture to a predetermined shutter opening time, close immediately. This way, the aperture is also the shutter function.
Note:
The mobile phone lens is generally used as a fixed aperture, Xiaomi mobile phones are no exception, which means the aperture is a fixed value. For example: Xiaomi 2 applies 2.0 lens aperture.