What are camera exposure and iso aperture?

Exposure refers to the process that the light emitted or reflected by the photographed object is projected onto the photosensitive film through the camera lens, causing chemical changes and development.

To clarify the word exposure, let's go back to pinhole imaging. Imagine a dark and closed room with a small round window on one wall and a photosensitive material (white asphalt, large film or CCD/CMOS) on the inner wall opposite the window. This is a big room camera. The room was dark before the small window was opened. When we open the small window, the light enters through the small hole and hits the film on the opposite wall, resulting in photochemical reaction (or photoelectric reaction, if it is CCD/CMOS), and the photo is born. This process is called exposure.

There are three factors that can affect whether a photo is exposed correctly: aperture, shutter speed and ISO (sensitivity). Among them, aperture and speed jointly determine the amount of light entering, and ISO determines the photosensitive speed of ISOCCD/CMOS. If the amount of light entering is not enough, you can open the aperture or lower the shutter speed; if it is not enough, you can improve the sensitivity (ISO). The disadvantage of large aperture is that the resolution is not as good as that of middle aperture. If the shutter speed is reduced, the picture may be pasted, and the quality of the picture will also decrease after the ISO is improved.

In digital cameras, ISO stands for the photosensitive speed of CCD or CMOS photosensitive elements. The higher the ISO value, the stronger the photosensitivity of photosensitive components. The calculation formula of ISO is H*S=0.8(S sensitivity, h is exposure). As can be seen from the formula, the higher the sensitivity, the lower the requirements for exposure. Deformation formula: H=0.8/s, under the same exposure, the exposure time at iso50 is twice as long as that at iso 100. Commonly used iso values are 50, 100, 200, 400, 1000, etc. К o500 and ISO1000 are used when the light is full, and the high iso value is used when the light is insufficient.

Aperture is a device used to control the amount of light entering the photosensitive surface of the fuselage through the lens, usually in the lens. We use the f value to represent the aperture size. For the manufactured lens, we can't change the diameter of the lens at will, but we can control the luminous flux of the lens by adding a polygon or circular aperture grating with variable area inside the lens. This device is called an aperture.