What are the mirrors and prisms of a camera?

A mirror is a mirror that you can see as soon as you take off your lens. Its main function is to hit the image in front of the lens on the pentaprism through the reflector, and then pass it to the photographer who is observing at the eyepiece. When taking pictures, the mirror will be lifted and the shutter curtain will be opened, so that the film or photosensitive element inside will be imaged by light. Pentagonal prism is the reflection device of SLR camera, and its function is to correct the left-right inverted image on the focusing screen, so that the image seen by framing is completely consistent with the direction of the scene directly seen, so that the operator can view and focus correctly. When the shutter is opened, the mirror rotates upward to make way for the light path, and the pentaprism is opaque.

A pentagonal prism is usually cut and polished by a whole piece of solid glass, and then the outer surface (except the two surfaces connected with the focusing screen and the viewfinder eyepiece) is coated with reflective materials to form a specular reflection inside.