People have been using camera and film for more than 100 years but there is still something magical about the process. Would you like to know how camera film works?Inside a cartridge of film is a long strip of plastic that has coatings on each side. The heart of the film is called the base, and it starts as a transparent plastic material known as celluloid. It is only 4 thousandths to 7 thousandths of an inch thick. The back side of the film is usually shiny and has various coatings that are important in processing the film so that we get images. But it is the other side of the film that we are most interested in, because this is where actually the images occur. There may be 20 or more individual layers coated here that 
together, are less than one thousandth of an inch thick. The majority of this thickness is taken up by a very special binder that holds the imaging component. Some of the layers coated on the transparent film do not form images, but are there are to filter light, or to control the chemical reactions. The imaging layers contain very, very tiny grains of silver-halide crystals. These crystals are the heart of photographic film. They undergo a photochemical reaction when they are exposed to light, so that we get a picture that is worth a thousand words.
