Why does the SLR lens on the face get fat, Zhihu?

Fat people who care too much about their image always feel that photographers have made themselves fat. In fact, the portrait taken with a standard lens or a medium-focus lens at a distance of 5 meters is the most realistic, and the close-range shooting with a wide-angle lens is prone to perspective deformation. For example, the stunning photos of self-portraits with beauty cameras, which are popular now, can make everyone have the same big eyes and oval face, which is very different from real people. SLR cameras can't use selfie sticks, which is not suitable for this shooting method.