What are the three functions of "aperture"?

The three functions of the "aperture" are:

Adjust the lighting. This is the basic function of the aperture. When the aperture increases, the light intensity increases; When the aperture decreases, the light intensity decreases. It solves the exposure problem together with the shutter speed.

Adjust and control the depth of field. This is an important function of aperture, and the depth of field is large or small; Small aperture and large depth of field.

Affect the imaging quality. This is the function of aperture that is easily overlooked. Any lens has an aperture with the best imaging quality, that is, it is least affected by various aberrations. This aperture is commonly known as the best aperture. The exact position of the optimal aperture can be measured by using special instruments.

In addition to providing automatic mode, high-end digital cameras usually have two options: aperture priority and shutter priority, so that you can decide a certain aperture value or a certain shutter value on some occasions, and then match the appropriate shutter or aperture respectively to present different depth of field (sharpness) or effects.

After we decide the aperture f value ourselves, the camera metering system will automatically choose the appropriate shutter speed (which can be an accurate stepless shutter speed) according to the light conditions at that time. A digital camera with an exposure mode dial usually engraves an "A" on the dial to indicate the aperture priority mode. Aperture prerequisite mode is suitable for photography that emphasizes the depth of field effect.

Because the focal length of digital camera is much shorter than that of traditional camera and the aperture of lens is small, it is difficult to produce narrow depth of field. Some digital cameras have a special portrait exposure mode, which uses built-in programs and a large aperture to blur the foreground and background.