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Camera Film

Is There a Better One?

This is a very full report on film that includes history, processing, etc. It totals 7 pages, but I put it on a very long sheet to save you people the hassle. This might take you a while to get through.

The history of making film for photo-cameras started in the year 1727, when a German professor of anatomy named Johann Schulze was experimenting with the manufacture of phosphorus. He made a precipitate of chalk in nitric acid and, to his astonishment, the chemical close to a laboratory window turned purple. Through a process of elimination, Schulze discovered that silver salts darkened when exposed to strong light. He decided that his observation was unique and important, but failed to use it for any worthwhile purpose.

However, other enthusiasts picked up his discovery. Jean Hellot applied silver nitrate to paper, in 1737. Some 40 years later, a Swedish chemist named Carl Scheele experimented with silver chloride, and discovered that it was sensitive mainly to the violet rays of the spectrum-he also found that blackened silver chloride was insoluble in ammonia, which acted as a fixing agent.

In 1835, an English mathematician by the name of William Henry Fox Talbot, had made the first successful negative image. He made it into a positive photo by contacting it with sensitized (very light-sensitive) paper. This created a double negative effect, simply put, a positive. This was the true beginning of the film we use today in our cameras, whether it is color negative or black&white negative.

Later, in the year 1837, a man named Louis Daguerre made a first photograph which he called a Daguerreotype. He used the same solution on a pewter plate, which got accidentally developed in mercury vapor from a broken thermometer in a cupboard. Shortly after that, he made a fixing solution out of salt.

The invention of color photography started in the year 1873, when Hermann Vogel, Professor of Photochemistry at the Technische Hochschule in Berlin, discovered that the collodion plate, normally non-sensitive to colors other than blue, could be made more sensitive to green by treating it with certain aniline (a colorless, oily, poisonous benzene derivative, C6H5NH2, used in the manufacture of rubber, dyes, resins, pharmaceuticals, and varnishes) dyes. This was called the orthocromatic plate. In 1906, Wratten and Wainwright in London, introduced the panchtromatic plate, which was sensitive to all the colors of the spectrum.

In 1891, Frederic Ives invented another way to photograph color. Three exposures/negatives, each sensitive to only one color (red, green, or blue), would have to be made, and then put together and viewed through a device called a Photochromoscope.

Rudolph Fischer, in 1912, made a film which had the same three emulsions held together on one single film. The first good color film came about 23 years later in 1935 when Leopold Mannes and Leopold Godowsky produced Kodachrome film at the Eastman Kodak Research Laboratories. Kodak is still considered to be one of the best films in the world today. In fact, Kodak Kodachrome film is still produced today and available in stores.

Now that you have read about the past history of photographic film, I will now introduce the definition and properties of the modern film that we use today:

Modern photographic film is essentially a thin plastic base coated with an emulsion. The emulsion is composed of gelatin within which tiny particles of light-sensitive salts have been suspended. The salts used are usually silver halides, such as silver iodide. The stored reaction to light (after the film has been exposed in the camera) is called the latent image and can be seen only after the film has been processed, or developed.

A special antihalation backing is applied to the underside of the base to prevent a halo effect or flare around bright objects when light bounces back and passes through the film a second time. Overcoats are applied to the film to minimize scratches and other unwanted impurities caused by the insides of the camera when the film moves through the camera and when it is processed.

Because of the nature of the silver halides in the emulsion, all light-sensitive photographic emulsions are sensitive to the violet and blue end of the visible spectrum. By adding different types of sensitizing dyes to the emulsion, film can be made to react to the entire spectrum or to limited portions of it. This response to different wavelengths of light is called color sensitivity. Film that is sensitive to light over the entire visible spectrum is called panchromatic and is the type used for most general photography.

By varying the amount and type of sensitizing dye used, the film's sensitivity to light intensity, which is called emulsion speed, may be adjusted. The speed figures were devised to indicate the minimum exposure necessary to produce a specified degree of blackening of the film. The American Standards Association (ASA) is one organization that has developed a system for measuring this speed. In this system, known as the ASA Exposure Index or simply ASA, the higher the numerical rating, the faster the film speed. Thus, a film rated at ASA 100 is twice as fast as and will require only half the exposure of a film rated at ASA 50. Today we call ASA ISO, which stands for International Standards Organization. It uses the same numbers as ASA does. The ASA does not really review film anymore because it is used all over the world. The ISO covers, as written on their website-Standardization of definitions, dimensions and recommended practice in the field of photography (specifically radiation sensitive recording media and their utilization); methods for testing, rating and classifying the performance characteristics of materials and devices used in photography; and methods, materials and processes used for photographic document reproduction- For the most part, the faster a film is, the more grainy it appears because of the clumping of the suspended particles in the emulsion of the film.

In a film negative, those areas containing the lightest objects (highlights) will have the greatest amount of density after processing, while the darkest objects (shadows) will have relatively less. Contrast is the middle range of tones between the very light and very dark elements in the original photograph. A high-contrast film will record only the highlights and shadows, or just white and black, while a medium- or low-contrast film will also record the middle tones.

White light can be created by superimposing, or adding together, equal amounts of red, green and blue light, the additive primary colors. Any two of these primary colors, when combined, form another color, the complement, or opposite, of the third primary color. For example, green and blue produce the color cyan, which is the opposite of red; red and blue produce magenta, the opposite of green; and green and red produce yellow, the opposite of blue. The colors cyan, magenta, and blue are referred to as the subtractive primaries because each represents the remaining color after one primary color has been subtracted from white light.

Color negative film is composed of three dye layers, each one sensitive to a separate component of light--red, green, or blue. During processing, these three layers form the dye colors cyan, blue, and magenta, respectively. Thus, red will appear as cyan, green as magenta, and blue as yellow on the negative. Unfortunately, I am not going to talk about black&white film in this report because it is near impossible to compare and is rarely used. I will, though, compare and tell some interesting facts about different kinds of color film in the next part of my report.

In some comparison tests done in the lab of Popular Photography Magazine on the latest brands of Fuji and Kodak films, the two leading film-making companies in the world, it was practically impossible to tell differences in the films, or say that one is better than the other. Kodak film proved to be a bit more contrasty than the Fuji brand. The Kodak film also seemed to have slightly better landscape tones, but facial tones seemed to be a little off. On the other hand, the Fuji film was less contrasty, giving a more smooth effect to the photographs compared. It also had slightly better skin tones that the Kodak film, but its landscapes did seem somewhat washed-out. The colors were a little dull on the landscape photos, but the Fuji film did look somewhat more promising in the portraits and people-photos.

So, as you can see, both of the films have their ups and downs. Both of the films that were tested were ISO 400, but other speeds may have different results. In general, ISO 200-400 films are ideal for regular photography. If you are shooting slides on slide film, you should look for an ISO of 64-100 because those films are much less grainy, making them much easier to project on a slide projector without any unsightly grain or clumped spots on your wall or screen, etc. Also if you plan to make very big enlargements of your prints to 8X10 or 11X14, you should use ISO 100-200 film. Also remember that slower films are best to be used in brighter conditions, while faster films are made to be more durable in darker conditions, where less light strikes the film. And finally, always keep in mind that if you buy a slower film (ex:100) to shoot in not-so-bright conditions, and if your camera can control shutter speed, you might end up with a slow exposure (1/60 sec. and slower) which may cause camera shake (natural movement of hands) to take affect and make your pictures blurry or shaky.

Here is another important thing that you need to know. DO NOT PUT FILM IN CHECKED BAGGAGE AT THE AIRPORT!!! Why? Because photographic film is very sensitive to those new X-ray machines that are used at airports today. It will not affect your shooting, but when you get your photos developed, you will find a very ugly yellow stripe going horizontally over every photo you have taken.

Now, for all of you curious people, this is how to develop film:

All of the developing for film is done in a darkroom, which is a room with no light (dough...). A safelight (special red lamp that emmits light that does not get exposed on film) is used for a little bit of lighting to see what you are doing. For color film, an accurate thermometer is needed to monitor solution temperatures. Some color films have capacities as low as plus or minus 0.45 deg C (plus or minus 0.25 deg F). In color negative film processing the function of the developer is almost identical to its function in standard black-and-white processing. It converts the exposed silver halide grains in the film emulsion into metallic silver. Wherever metallic silver is present, the developer interacts with color-forming agents in the three different layers to form color dyes. The next step is the bleach, which stops the development process and converts the metallic silver back into silver halide. The fixer step removes all of the soluble silver salts in the film. The film is then washed to remove traces of fixer. Next, a stabilizer is added, which hardens the emulsion and extends the life of the color dyes. The stabilizer solution also contains a wetting agent, which helps prevent drying marks on the negative. The next step is to make a [positive] print

A positive print is generally made from a negative by placing the negative in an enlarger, which is essentially a projector that focuses the negative image at a specified degree of magnification, for a specified period of time, through a lens, onto a piece of sensitized photographic printing paper. An alternative procedure is to make a contact print: the emulsion side of a negative is pressed into contact with the emulsion side of a piece of printing paper; light is then passed through the negative to expose the emulsion, resulting in a print that is the same size as the negative. The remaining steps are the same for both methods.

The exposed paper is put into the developer solution, which converts the exposed silver halides into metallic silver. With color film, the dye couplers combine with the developer to form the color image wherever the metallic silver is present. The bleach-fix step converts the metallic silver into a soluble silver salt solution and removes it, along with any remaining unexposed silver halide grains. The paper is next washed to remove any trace of fixer and then dried.

The actual process can be carried out in a variety of ways. A tray system involves a series of shallow dishes containing the chemical solutions. The paper is dipped in each tray successively for the specified period of time and then laid flat to dry. In the drum method the paper remains inside a light-tight cylinder while the solutions or wash water are poured in and out. After processing is completed the paper is removed for drying.

For large-scale or industrial film and paper processing, modern automatic processing machines are used. Exposed materials are inserted at one end, and processed film or paper that is dry and ready to use emerges at the other end. Developing, rinsing, fixing, washing, and drying are all handled automatically within the machine.