A camera has a diaphragm, an opening that gets bigger or smaller to let in the right amount of light for a clear picture. In your eye, the iris does the same thing. The iris is a thin layer of tissue at the front of your eyeball.
A camera has a lens that focuses the light into a clear picture. Your eye also has a lens to focus the light.
In a camera, the light forms a picture on the IRIS film. In your eyes, the picture is formed on the retina, the inner layer of your eyeball at the back of your eye. Because light rays bend in the eye and in a camera, the picture is upside down on both the film and the retina.
But in the eye, the brain changes the picture to a right-side-up image, and in the camera, when the film is processed, it is simply held right-side up.
