Emulsion
Black and white film is made out of a thin, plastic strip. One side of the black and white film is covered in a substance called emulsion. The emulsion is often made out of gelatin, just like the wiggly dessert. This emulsion holds chemicals, such as silver bromide, that are light sensitive. The chemicals are altered when light is shined on them. This is why it is important to keep film in a light-tight container until it is ready to be loaded in the camera.
Exposure
When the film goes in the camera, only a small end is exposed to light. Once the camera is shut and the film is advanced, an unexposed portion of film will be positioned directly behind the shutter. In order to produce a quality photo, one must point the camera at an object and set the camera to the correct light exposure. To set an exposure, the camera person monitors the light using the camera's light meter and then makes f-stop and shutter-speed adjustments. The f-stop controls the size of the aperture or hole within the shutter. The shutter speed controls how quickly the shutter opens and closes to expose the film to light. When the photo is snapped, the shutter opens, exposing the film to the light reflected by the image that is streaming through the aperture. That light becomes recorded on the light-sensitive chemicals in the emulsion, and that piece of film becomes an exposure.
Development
During the development stage, the film is immersed in a liquid developer. The developer activates the silver, and it becomes darker where the light has shined, thus producing a negative image. Then, the film is fixed. It is important to keep the film immersed for the suggested development time for the brand of developer being used. One must also occasionally agitate the film to remove any air bubbles that might prevent development on spots of the film. After development, a hypo-sulphate solution is poured over the film, removing the bromide from the emulsion and making it so the film is no longer light sensitive. This process is called fixing. Once the fixing is complete, the film can be exposed to light without any fear of losing the negative image. It is important to dry the film and store it carefully to make sure to avoid dust spots and streaking.
Tags: exposed light, film immersed, film light, important keep, important keep film
