Photographic film in the context of "Infrared"

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⭐ Core Definition: Photographic film

Photographic film is a strip or sheet of transparent film base coated on one side with a gelatin emulsion containing microscopically small light-sensitive silver halide crystals. The sizes and other characteristics of the crystals determine the sensitivity, contrast, and resolution of the film. Film is typically segmented in frames, that give rise to separate photographs.

The emulsion will gradually darken if left exposed to light, but the process is too slow and incomplete to be of any practical use. Instead, a very short exposure to the image formed by a camera lens is used to produce only a very slight chemical change, proportional to the amount of light absorbed by each crystal. This creates an invisible latent image in the emulsion, which can be chemically developed into a visible photograph. In addition to visible light, most films are sensitive to ultraviolet light, X-rays, gamma rays, and high-energy particles. Unmodified silver halide crystals are sensitive only to the blue part of the visible spectrum, producing unnatural-looking renditions of some colored subjects. This problem was resolved with the discovery that certain dyes, called sensitizing dyes, when adsorbed onto the silver halide crystals made them respond to other colors as well. First orthochromatic (sensitive to blue and green) and finally panchromatic (sensitive to all visible colors) films were developed. Panchromatic film renders all colors in shades of gray approximately matching their subjective brightness. By similar techniques, special-purpose films can be made sensitive to the infrared (IR) region of the spectrum.

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Photographic film in the context of Filmmaking

Filmmaking or film production, is the process of creating a motion picture. It involves a number of distinct stages, including an initial story idea or commission, followed by screenwriting, casting, pre-production, shooting, sound recording, post-production, and screening the finished product before an audience, which may result in a film release and exhibition. The process is nonlinear, in that the filmmaker typically shoots the script out of sequence, repeats shots as needed, and puts them together through editing later. Filmmaking takes place in a variety of economic, social, and political contexts around the world, and uses a wide range of technologies and cinematic techniques. While originally films were recorded on photographic film, most modern filmmaking is now digital.

The production of a film typically consists of five major stages. The first is development, where the initial idea for the film is explored, rights to intellectual property may be secured, the screenplay is written, and financing is obtained. This is followed by pre-production, where all the arrangements and preparations for the shoot are made, including hiring cast and crew, scouting and securing locations, and constructing sets. The third stage is production, which is when the raw footage and other elements of the film are recorded.

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Photographic film in the context of Photography

Photography is the art, application, and practice of creating images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed in many fields of science, manufacturing (e.g., photolithography), and business, as well as its more direct uses for art, film and video production, recreational purposes, hobby, and mass communication. A person who operates a camera to capture or take photographs is called a photographer, while the captured image, also known as a photograph, is the result produced by the camera.

Typically, a lens is used to focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed exposure. With an electronic image sensor, this produces an electrical charge at each pixel, which is electronically processed and stored in a digital image file for subsequent display or processing. The result with photographic emulsion is an invisible latent image, which is later chemically "developed" into a visible image, either negative or positive, depending on the purpose of the photographic material and the method of processing. A negative image on film is traditionally used to photographically create a positive image on a paper base, known as a print, either by using an enlarger or by contact printing.

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Photographic film in the context of Photograph

A photograph (also known as a photo, or more generically referred to as an image or picture) is an image created by light falling on a photosensitive surface, usually photographic film or an electronic image sensor. The process and practice of creating such images is called photography.

Most photographs are now created using a smartphone or camera, which uses a lens to focus the scene's visible wavelengths of light into a reproduction of what the human eye would perceive.

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Photographic film in the context of Camera

A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photography and videography, cameras have played a significant role in the progression of visual arts, media, entertainment, surveillance, and scientific research. The invention of the camera dates back to the 19th century and has since evolved with advancements in technology, leading to a vast array of types and models in the 21st century.

Cameras function through a combination of multiple mechanical components and principles. These include exposure control, which regulates the amount of light reaching the sensor or film; the lens, which focuses the light; the viewfinder, which allows the user to preview the scene; and the film or sensor, which captures the image.

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Photographic film in the context of Exposure (photography)

In photography, exposure is the amount of light per unit area reaching a frame of photographic film or the surface of an electronic image sensor. It is determined by exposure time, lens f-number, and scene luminance. Exposure is measured in units of lux-seconds (symbol lx⋅s), and can be computed from exposure value (EV) and scene luminance in a specified region.

An "exposure" is a single shutter cycle. For example, a long exposure refers to a single, long shutter cycle to gather enough dim light, whereas a multiple exposure involves a series of shutter cycles, effectively layering a series of photographs in one image. The accumulated photometric exposure (Hv) is the same so long as the total exposure time is the same.

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Photographic film in the context of Photographic emulsion

Photographic emulsion is a light-sensitive colloid used in film-based photography. Most commonly, in silver-gelatin photography, it consists of silver halide crystals dispersed in gelatin. The emulsion is usually coated onto a substrate of glass, films (of cellulose nitrate, cellulose acetate or polyester), paper, or fabric. The substrate is often flexible and known as a film base.

Photographic emulsion is not a true emulsion, but a suspension of solid particles (silver halide) in a fluid (gelatin in solution). However, the word emulsion is customarily used in a photographic context. Gelatin or gum arabic layers sensitized with dichromate used in the dichromated colloid processes carbon and gum bichromate are sometimes called emulsions. Some processes do not have emulsions, such as platinum, cyanotype, salted paper, or kallitype.

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Photographic film in the context of Latent image

A latent image is an invisible image produced by the exposure to light of a photosensitive material such as photographic film. When photographic film is developed, the area that was exposed darkens and forms a visible image. In the early days of photography, the nature of the invisible change in the silver halide crystals of the film's emulsion coating was unknown, so the image was said to be "latent" until the film was treated with photographic developer.

In more physical terms, a latent image is a small cluster of metallic silver atoms formed in or on a silver halide crystal due to reduction of interstitial silver ions by photoelectrons (a photolytic silver cluster). If intense exposure continues, such photolytic silver clusters grow to visible sizes. This is called printing out the image. On the other hand, the formation of a visible image by the action of photographic developer is called developing out the image.

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Photographic film in the context of Photographic processing

Photographic processing or photographic development is the chemical means by which photographic film or paper is treated after photographic exposure to produce a negative or positive image. Photographic processing transforms the latent image into a visible image, makes this permanent and renders it insensitive to light.

All processes based upon the gelatin silver process are similar, regardless of the film or paper's manufacturer. Exceptional variations include instant films such as those made by Polaroid and thermally developed films. Kodachrome required Kodak's proprietary K-14 process. Kodachrome film production ceased in 2009, and K-14 processing is no longer available as of December 30, 2010. Ilfochrome materials use the dye destruction process. Deliberately using the wrong process for a film is known as cross processing.

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Photographic film in the context of Contact print

A contact print is a photographic image produced from film; sometimes from a film negative, and sometimes from a film positive or paper negative. In a darkroom an exposed and developed piece of film or photographic paper is placed emulsion side down, in contact with a piece of photographic paper, light is briefly shone through the negative or paper and then the paper is developed to reveal the final print.

The defining characteristic of a contact print is that the resulting print is the same size as the original, rather than having been projected through an enlarger.

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