What effect does sensitivity have on photography?

Sensitivity has two main effects on photography: 1, speed, the higher the sensitivity, the faster the shutter speed; 2, image quality, the lower the sensitivity, the finer the image quality. The higher the sensitivity, the greater the noise of the image quality, that is, the lower the definition of the photo. Sensitivity, also known as ISO value, is a measure of the sensitivity of a negative to light. Sensitivity can effectively improve the brightness of photos. When the picture in the camera is too dark, the sensitivity can be increased, which can effectively solve the problem of low brightness of the picture. For example, when the camera parameters are displayed as "F4.0,1160s, ISO F4.0" during shooting, you can find that the picture in the camera is rather dim. At this time, the sensitivity can be adjusted to "ISO 1000" without setting other parameters, so that the color of the picture becomes brighter and brighter. But what needs to be known is that only by adjusting the sensitivity to enhance the brightness will the noise of the dim picture be increased. So this simple setting method is not suitable for shooting in too dark environment.