The schematic diagram represents a cross-section of a camera and the various parts present in it.
Overall, the light rays enter through each lens, where the rays converge. After the rays are sensed, the rotating mirror reflects the image to a screen and this image is further deviated by a five-sided prism to view the captured light through the eyepiece.
The light enters through a stack of lenses lined up inside a lens holder. These light rays converge to form a clear image. The light rays that travel through the main part of a camera get detected by a digital sensor. As the shutter is opened to admit the light, the mirror begins to rotate at 90 degrees hinged at the top, which is placed in front of the shutter.
The rotating mirror reflects the light onto a screen called a focusing screen. Then the light is again rotated by 90 degrees with the help of a pentaprism, which displays the reflected light through an eyepiece. Thus, through various stages of reflection of light, we could see an image through the eyepiece.