Press and hold the round key, and then roll the impeller to adjust the aperture.

: pore size

The function of the aperture is to determine the amount of light entering the lens. When the shutter is constant:

The smaller the value behind f, the larger the aperture, the more light entering, the brighter the picture, the narrower the focal plane and the more blurred the background of the subject;

The larger the F value, the smaller the aperture, the less light entering, the darker the picture, the wider the focal plane, and the clearer the front and back of the subject.