Basic Technology Light is the essential ingredient in photography. Nearly all forms of photography are based on the light-sensitive properties of silver-halide crystals, chemical compounds of silver and halogens (bromine, chlorine, or iodine). When photographic film, which consists of an emulsion (a thin layer of gelatin) and a base of transparent cellulose acetate or polyester, is exposed to light, silver-halide crystals suspended in the emulsion undergo chemical changes to form what is known as a latent image on the film. When the film is processed in a chemical agent called a developer, particles of metallic silver form in areas that were exposed to light. Intense exposure causes many particles to form; weak exposure, few. The image produced in this manner is called a negative because the tonal values of the subject photographed are reversed; that is, areas in the scene that were relatively dark appear light, and areas that were bright appear dark. The tonal values of the negative are reversed again in the photographic printing process or, when preparing color transparencies (slides), in a second development process. Photography, technique of producing permanent images on sensitized surfaces by means of the photochemical action of light or other forms of radiant energy.

      

Motion Picture, continuous sequence of transparent still photographs, in black and white or color, exposed onto long strips of specially treated cellulose acetate and projected in rapid succession onto a screen to give the optical illusion of motion. Modern motion pictures are usually accompanied by a synchronized sound recording to heighten the illusion of reality. The terms film, moving pictures, or movies in the United States and cinema in Great Britain are commonly used synonyms for the term motion pictures. PLEASE BE AWARE that Basic properties & techniques of Still Life Photography exist in Motion Photogaphy.

      

Emulsion Colors Emulsions are thin, gelatinous, light-sensitive coatings on film that react chemically to capture the color and shadings of a scene. The four layers pictured above show the same image as it would appear on different emulsions in photographic film after the first stage of developing. For black-and-white photographs, only one emulsion is required, because it is the amount of light, not the color, that activates the chemical reaction. Color film requires three layers of emulsions, each of which is sensitive to only one of the primary colors of light: blue, green, or red. As light passes through the layers, each emulsion records areas where its particular color appears in the scene. When developed, the emulsion releases dye that is the complementary color of the light recorded: blue light activates yellow dye, green light is magenta, and red light is cyan (bluish-green). Complementary colors are used because they produce the original color of the scene when the film is processed. Photographic Film Photographic films vary in the way they react to different wavelengths of visible light. Early black-and-white films were sensitive only to the shorter wavelengths of the visible spectrum, that is, to light perceived as blue. Later, colored dyes were added to film emulsions to make the silver halides responsive to light of other wavelengths. These dyes absorb light of their own color, making silver halide particles sensitive to light of that color. Orthochromatic film, incorporating yellow dyes in the emulsion and sensitive to all light but red, was the first improvement on simple blue-sensitive film Color Film Color films are more complex than black and white because they are designed to reproduce the full range of color tones as color, not as black, white, and gray tones. The design and composition of most color transparency films and color negative films are based on the principles of the subtractive color process, in which the three primary colors, yellow, magenta, and cyan (blue-green), are combined with their complements to reproduce a full range of colors. Such films consist of three silver halide emulsions on a single layer. The top emulsion is sensitive only to blue. Beneath this is a yellow filter that blocks blues but transmits greens and reds to the second emulsion, which absorbs greens but not red. The bottom emulsion records reds.

      

Film Speed Film is classified by speed as well as by format. Film Speed is defined as an emulsion's degree of sensitivity to light, and determines the amount of exposure required to photograph a subject under given lighting conditions. The manufacturer of the film assigns a standardized numerical rating in which high numbers correspond to “fast” emulsions and low numbers to “slow” ones. Low-speed films generally are rated from ISO 25/15 to ISO 100/21, but even slower films exist. Kodak's Rapid Process Copy Film, a special process film, has an ISO rating of 0.06/-12. Films in the ISO 125/22 to 200/24 range are considered medium speed, while films above ISO 200/24 are considered fast. In recent years, many major manufacturers have introduced superfast films with ISO ratings higher than 400/27. And certain films can be pushed well beyond their ratings by exposing them as though they had a higher rating and developing them for a greater length of time to compensate for the underexposure.

      

Developing a Black and White Print A rose was the subject of this 8 x 10 inch black-and-white photograph and contact print. After the film was exposed, chemical changes formed an upside-down and backwards image of the rose, called the latent image. The latent image is invisible, and the film must be placed in a developer before a negative of the rose is visible. The negative shows the darkest regions of the rose as the lightest, and the lightest as the darkest. This happens because the chemicals on the film (called the emulsion) darken in response to light. A print is made by placing the negative between a glass plate and light-sensitive paper and exposing it to a source of light. This re-reverses the light and dark regions of the flower. Next, the print paper is placed in a paper developer, and a print the same size as the negative is produced. Developing and Printing The latent image on film becomes visible through the process called developing—the application of certain chemical solutions to transform the film into a negative. The process in which this negative is used to create a positive image is called printing; the image is called a print. Film is developed by treating it with a weak reducing alkaline chemical, the developing solution, or developer. This solution reactivates the process begun by the action of light when the film was exposed. The effect is to further reduce the silver-halide crystals in which metallic silver had already formed, so that large grains of silver form around the minute particles that make up the latent image.

      

Types of Motion Pictures The most significant categories of motion pictures are feature films, documentaries, and animated films, commonly called cartoons. The procedures involved in making these different types of films are similar, though they vary in technique and in degree. Feature Film The feature is produced in three stages: preproduction, production, and postproduction. The development, or preproduction, stage is the period of time when the story, or property, to be produced is procured. An option is a contract giving the producer the rights to produce the story. The option, like any contract, states the terms and conditions under which the property owner will surrender the rights, including the length of time the property may remain stagnant should the producer be unable to gather financing to produce the film. Options may be renegotiated when they expire. Also during this stage, the script is finalized, the financing is obtained and budget designed, and the director and key personnel are selected. The production stage is the period of time when the filming of the story occurs. The length of this period, the number of crewmembers hired for the production, and many other elements are determined by the size of the budget. Most feature films require that specific schedules be followed so that the motion picture will be shot on time and within the established budget. The postproduction and editing stage is the period of time when all the parts of the film, which have been shot out of sequence, are put together to make one cohesive story. It is also the time when the search for the best arrangement for the distribution of the film takes place, if such an arrangement was not made earlier

      

Microsoft Illustrations & Literature Courtesy of: "Photography," Microsoft (R) Encarta. Copyright (c) 1994 Microsoft Corporation. Copyright (c) 1994 Funk & Wagnall's Corporation. "Motion Picture," Microsoft (R) Encarta. Copyright (c) 1994 Microsoft Corporation. Copyright (c) 1994 Funk & Wagnall's Corporation. UNIQUE VISITORS