The alias name is descriptive of 35 mm film width, but in reality, the film is a bit narrower than 35 mm: it is actually about 1 3/8 inches wide, and 34.9 mm because at start, 135 film was made by cutting other film standard size - 2 ¾ inch - in half.
The four main types of films; color, black and white printing and Slide, although black and white slide film has become very rare.
The printing film is also known as "negative" because it produces a complete reversal of the captured image (ie, negative), where light areas appear dark, dark areas become light and color (if applicable ) are also in their complementary colors. Film "Reversal" produces a positive image on a transparent basis. The treated film contains a precise color reproduction and light and shadow, and does not require additional treatment. Reversal film produced "transparency", which are usually mounted on a frame or plastic card, called "slides".
All films have a "value speed", which is a measure of the sensitivity of film to light. Films with a lower speed are relatively insensitive to light, require greater exposure to it, and are called movies " slow. "higher speed films are relatively more sensitive to light, require shorter exposures, and are called" fast "films. The system DIN (Deutsches Institut für Normung) was published in 1934 and is a logarithmic scale, usually consisting of one or two digits.
The ASA scale is easier to work, because the relationship between the film speed is easier to understand. For example, an ASA movie 200 was twice as fast as a 100 ASA film and a film of 400 ASA is two times faster than film 200 ASA. In other words, using 400 ASA film, preferably 200 ASA allows the camera to a configuration with a lower aperture f-stop, shutter or a higher speed step. Furthermore, when using the scale of DIN was not so easy to understand - the hull - a film DIN 24 was twice as fast as DIN 27 and DIN 21 movie movie was twice as fast as a 24-Din film (you had to learn the increment speed).
In 1974, a new ISO (International Standards Organization) scale was adopted by the photographic industry, and this effectively combined the old ASA and DIN scales in one. In other words, ASA 100 or 21 has become the standard DIN ISO 100/21, and ASA 200 or 24 has become the standard DIN ISO 200/24. Cameras made before the mid-1980s may have ASA or DIN scales, or both. GOST ISO conversion tables are available on the internet.
The relevance of the speed of the film itself, which extends the capabilities of a camera according to different lighting conditions. Film is made of small pieces of money that appear under magnification with sand gains. Large grains of silver to give greater sensitivity film to light for faster films tend to have a more granular texture, while the slow films have fine grains of silver, and to capture sharp images with much finer levels of texture due to the film. Digital age equivalent today granules and fine-grained descriptions would be "noise" and "high-definition images."
For this reason, the speed of the choice of film is often a compromise between ease of firing (ie, the ability to use higher shutter speeds / smaller openings), and the quality of the desired photograph . Fortunately, most of the filmmakers (and good retailers) describe the grain qualities of their products, which allows the photographer to choose the film that best suit their needs based on the speed and grain.
Today, the film four major manufacturers that have fueled once the increase in amateur photography's popularity is still in the business of making films: Agfa, FUJICA, Ilford and Kodak (plus a few others whose names have less praise). In short, a film with a 35mm camera is described by a combination of: identifying the size 135 or 35mm, color or black & white, negative or reverse (print or slide), ISO sensitivity and granularity. Some manufacturers give their films a catchy name that summarizes all this information in a word, as ColorPlus or Velvia.
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