How to choose exposure combination when shooting?

Exposure is the most complicated link in photography. When choosing an exposure combination, you should first consider what important exposure effect you need and what exposure is appropriate. Overexposure? Still underexposed? It all depends on the specific needs. As far as digital SLR cameras are concerned, there are several factors that affect exposure: aperture, shutter and ISO. When there is no special demand, do what we need when the exposure is right. Simply put, in the case of sufficient light, you should choose a relatively low ISO, 100 or 200, and the combination of aperture and shutter is appropriate. When the light is insufficient, the ISO can be improved appropriately, but if it is not necessary, it can be not too high to avoid noise, and the aperture can be enlarged as much as possible to obtain a faster shutter speed, which can minimize the picture blur caused by the slow shutter speed. If you are not sure, you can shoot with P file first. Of course, the first step in choosing exposure combination is photometry. To choose the exposure combination according to the photometric results of the camera, many factors will also interfere with the photometric system of the camera. The most typical is the so-called "white plus black minus" principle, that is, if there is a large area of objects that are obviously brighter than the surrounding environment, or there are reflective things (such as glass, mirrors, water, etc.). ) In the range of framing, generally speaking, in order to obtain normal exposure, one-level exposure should be added on the basis of camera metering; On the other hand, if there is a large area of objects that are obviously darker than the surrounding environment in the framing range, generally speaking, in order to obtain normal exposure, the first exposure should be reduced on the basis of camera metering. Wait, wait, wait.