- A camera functions very much like the human eye. Both see light that is reflected from the object being viewed. It transmits itself to the eye as sight or the camera as a picture in film or digital form. Light rays diffuse and bounce randomly from the myriad of objects around us so in order to see or form a picture, the rays need to be focused into a coherent form. To begin, the light enters the eye through the cornea and, like a camera's aperture, the pupil enlarges or contracts to ensure that the right amount of light enters the eye.
- When light enters the eye, it focuses on cells on an area at the back of the eye that is sensitive to light, which is known as the retina. Just as a camera responds to light entering it to form an image on film or digitally, the retina forms an image by transmitting the light to the brain by means of the optic nerve.
- Light rays bend when they enter the camera so that an image is upside down, a situation that's corrected when the picture is formed digitally or in film processing. The same is true of the light rays that bend on the retina but in that case, the brain actually does the work of correcting the image for us.
- The human eye, like a camera, can view tones of gray and the various shades of color (unless the person happens to be color blind, of course.) Both the eye and the camera can see near and far, judge size, register depth perception and see movement. However, the human eye can only see in visible light. Specialized cameras, films and digital photography can go much further by capturing images that are far beyond the eye's capability. The camera can show heat images and X-ray views, stop motion or capture images too fast for the human eye, such as a bullet in mid-flight, and cameras can be designed to view everything from the smallest particle to the planets at extreme distances.
