How to set the ISO sensitivity on the camera?

Although digital cameras do not use film, in order to clearly express the camera's sensitivity to light, this concept is borrowed to express different sensitivities under different light conditions. The higher the ISO value, the more sensitive the image sensor is to light, and the less light is needed when the photoreceptor works with high sensitivity, which is easy to produce noise. If the ISO value is set low, the sensitivity of the photoreceptor is not high, and more light is needed when working, so it is not easy to produce noise. If the lighting conditions at the shooting site allow, try to set a lower sensitivity, so as to ensure the delicate and smooth image. In order to improve the imaging quality with high ISO value, some manufacturers have adopted various noise reduction technologies. Although these technologies improve the image quality, they still can't eliminate the noise fundamentally. It is found that under the same illumination conditions, the image quality of low ISO value is obviously better than that of high ISO value. The ISO value of a digital camera can be selected between 50 and 6400 (the numerical areas of different cameras are different), and the setting of ISO value is very important for image quality. How to define ISO values? Generally, the ISO value below 200 is a low value, and above 800 is a high value. When setting, the first factor to consider is whether there is bright light at the shooting scene. If the light is good, you can set the ISO value to 100. If you shoot in a dark environment and don't have a tripod, you can't complete a long exposure with a hand-held camera. At this time, you can choose a higher ISO value, so as to minimize noise and get a proper exposure, which requires you to choose between ISO value and exposure speed.