How does a camera take pictures?

When you press the picture-taking button on a camera, you open the shutter and let light inside for a fraction of a second. The light passes through a lens that focuses it on film, leaving a record there of what the camera “saw” during that buttonpressing instant. The film is coated with light-sensitive chemicals that save the impression, but it usually has to be placed into a bath of other chemicals to make an image appear and remain permanently. The film is developed into negatives, on which appear images that look very different than those that were photographed: dark shades appear light, light shades appear dark, and colors are the opposite of what they should be. But when light passes through these negatives onto special photo paper, which is also developed using chemicals, the images that appear are normal again—exact copies of the photographed scenes. With “instant” cameras, developing chemicals are contained inside, treating the film right away. A picture pops out on photo paper, its image forming while you wait. Digital cameras work the same way that television cameras do: Instead of using film, they make electronic pictures. The pictures are loaded onto a computer, where they can be altered in size, shape, and color, and printed out.