What are the advantages and disadvantages of adjusting IS0 to 100 during photography?

The ISO sensitivity means that if you choose a higher ISO sensitivity under the same EV exposure value, you can get the same exposure with a faster shutter speed under the same aperture. On the contrary, a smaller aperture can be used to maintain correct exposure without changing the shutter. Therefore, when shooting in dim light, you can often choose a higher ISO sensitivity. Of course, for SLR cameras, you can also choose to use a larger caliber lens to improve the luminous flux. For ordinary digital cameras, because they use a fixed lens, only by improving the ISO sensitivity can they adapt to shooting in dim light, especially when auxiliary light cannot be used. The film used in traditional cameras can improve the sensitivity of the film by controlling the sensitivity of dyes to light. However, the improvement of sensitivity will reduce the image clarity, increase the contrast, that is, reduce the dynamic range. The photosensitive element of digital camera belongs to active element and has dark current. Set the cut-off current in normal mode, and the part with noise interference will not be used. In the high sensitivity mode, the noisy parts are used, and these background noises are reflected as random noises in the image. As long as the photosensitive element is not improved and the aperture is not changed, it is impossible to really improve the problem. At most, the algorithm is used to weaken the intuitive feeling of noise, which is why high iso cameras often have larger lenses and larger photosensitive elements. Therefore, in the case of poor lighting conditions, we should first consider the application of auxiliary light (flash and reflector), then consider the use of tripod and anti-shake when auxiliary light cannot be used, and finally consider the method of improving ISO sensitivity. For places with dark light, such as shooting stage, where flash is not allowed or tripod is inconvenient to use, you can try to choose a digital camera with a larger aperture and a shorter focal length, and a SLR digital camera can choose to shoot with a larger lens (of course, a larger aperture will also reduce the depth of field). Night shooting often uses a larger aperture and a longer exposure time. If you choose a higher ISO sensitivity, it will inevitably produce noise and noise. At this time, you can use a tripod and a selfie, and you may use a cable to release it. Choose a lower ISO sensitivity to avoid noise and noise.