When shooting with a SLR camera, the sun enters the composition. Is it possible for the sun to focus through the lens and damage the camera?

This situation is possible. Even if the removed lens is not covered with the front cover and the back cover, the sunlight will focus and even cause a fire. However, if the shutter speed is fast enough and the composition shooting time is short, it will generally not be damaged (the reflector will reflect most of the sunlight to the viewfinder), but the eyes and lens must not stare for a long time, otherwise it will seriously damage the eyes and shutter curtain. The image sensor is less damaged, but if the shutter time is long, it will also burn out the photosensitive element.

If there is a sun in the composition, it is best to use a medium gray filter.

If the mirror is used for pre-lifting, it is forbidden to point the lens at the sun, otherwise the shutter curtain will be burned immediately.

Consumer cameras are forbidden to synthesize the sun because of their structural characteristics (no mirrors), otherwise it is very easy to burn out the CCD.