![]() ![]() The lightest areas of the image appear darkest and the darkest areas appear lightest. It's called a negative because it is the reverse of the actual image. This exposure can then be seen once the film is developed.Ī film negative is the image created on a strip or sheet of photographic print film, after it is exposed to light. When exposed to light, these crystals chemically change (with the change being proportional to the amount of light they are exposed to), which is what creates the imprinted image (often called "exposure") in the emulsion (chemical mixture) on the strip of film. The sizes and varying characteristics of the crystals determine a film's sensitivity, contrast and resolution. These layers are made up of a gelatin emulsion containing microscopically small light-sensitive silver halide crystals. Emulsion is a scientific word for "mixture," and in most cases, when talking about photographic film, it is referring to those light-sensitive layers. A lot of times you'll hear the word "emulsion" when referring to the chemical components of film. The combination and order of these layers is different for each type of film (color, black & white, slide, instant, etc). Photographic film is created by coating a transparent strip of plastic with a series of chemical layers that are sensitive to light. This is often called Sheet Film because each frame is a separate sheet, not on a consecutive roll or spool like 135 and Medium Format films. Large Format: Also known as Sheet Film, Large Format is any film with a single frame size of 4x5 inches or larger. 220 Medium Format film is twice as long as 120, and does not have a protective backing paper on it (which allows the longer 220 film to fit in the same spool as 120 film). Typical sizes/ratios are 6x7cm (10 exposures), 6圆cm (12 exposures), and 6x4.5cm (16 exposures). 120 film generates anywhere from 10 - 16 exposures per roll, depending on the camera used. It comes in two main lengths, 120 and 220, with 120 being the most common. Medium Format: Larger than 135 film, it is 61mm wide and does not have perforated edges (the film moves from one spool to another in-camera when shooting - no need to rewind after finishing a roll). The film has perforated edges, which allow the film to be wound to and from a spool within the camera back. The larger the negative or transparency, the more information within and less distortion or grain visible when that image gets enlarged.ġ35: Also referred to as 35mm, it has a standard frame size of 36x24mm, and most frequently produces 24 or 36 exposures. Within each of these film sizes there are a variety of aspect ratios that can be created in a frame, based on the camera design used. It's important to realize that the ISO speed of a film is a fixed value and cannot be changed in the camera like in a digital camera.įormat: Film format is determined by size and shape of the film. ISO 50 film is a slow film because it is less sensitive to light and requires more exposure to light in order to produce the same image density. For example, film with ISO 1600 is a fast film because it is highly sensitive to light and requires a short exposure time/less light in order to create proper density. The term film "speed" derives from how quickly a film emulsion can be properly exposed. ![]() The lower the ISO number, the less sensitive to light, and the higher the number, the more sensitive to light. "ISO" stands for International Standards Organization, and is an industry standardized scale for measuring sensitivity to light. Speed: Film speed is defined by a film's sensitivity to light, and is most commonly referred to as ISO. Reversal film produces a positive transparency when exposed and developed, and is often called "Slide film" or "Chrome film." Negative film, when exposed and developed, creates a transparent negative. Type: The two basic film types are Negative and Reversal. There are three main characteristics that define film: Type, Speed and Format. ![]()
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