A camera is a device used to take photographs. A camera is a dark box that holds light sensitive film on one end with a small opening or aperture on the opposite end of the camera.
Light travels through the aperture and exposes the film on the back of the camera.
A camera works by allowing light from the aperture in the front of the camera to hit the lens and produce an inverted image on the film at the back of the camera. The camera type we are focusing on is the SLR camera. The single-lens reflex camera has a single lens that uses a mirror to reflect an image on to the film on the back of the camera. When the shutter release button is depressed, the shutter door opens. The mirror lifts out of the way and allows the light to expose the film.