David Culver, age 13, of DeKalb, I11., for his question:

HOW IS A PHOTOGRAPH MADE?

A camera, in simplest terms, is a box with a small opening at one end. Light sensitive film is placed in the dark interior of this box. A shutter covers the opening into which is placed a glass lens. When the shutter is opened, light passes through the lens which bends the light rays so that they form a sharp image or picture on the piece of film.

After the image has been put on the film, it must go through a complicated chemical process called developing.

Some cameras adjust themselves prior to picture taking time, but with others it is important that you first set the shutter speed, adjust the size of the lens opening and then focus the camera on the subject you have selected for photographing.

Here's how the photograph is actually made:

Your camera lens gathers in the light rays reflected from subjects in the scene you are photographing. On the thin sheet of plastic film is a coating called an emulsion. The emulsion is made up of tiny grains of silver salts held together by a jellylike substance.

The silver salts are sensitive to light and change when light hits them. Light colored objects reflect a great deal of light and the silver salts undergo a great change. Dark objects reflect only little light, so there is little change on the film. In this way, the lights and darks reflected from a scene make an image on the emulsion.

After developing, the film becomes a negative. The negative is used to print your final picture. Printing of a photograph reverses the light and dark tones of the negative. As a result, the paper printing shows the scene as you originally photographed it.

The camera was probably invented during the early 1500s. Many people are given credit for the invention, including Leonardo da Vinci, the great Italian artist.

The first person to make a permanent image was Joseph Niepce, a French physicist. He used a light sensitive metal plate in a camera and then used an engraving process to set the image. Niepce's first picture was made in 1826.

The word "photography" means writing or drawing with light. A camera picture is actually a picture drawn with rays of light.

More than half of the families in the United States own cameras and millions of pictures are taken by people every year.

Photography is one of the world's most popular hobbies. Many photographers join camera clubs where they hold regular meetings and discuss the joys and problems of photography with other photographers.