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Microfilm Reader
A microfilm reader is a device used in projecting and magnifying images stored in microform to readable proportions. Microform includes flat film, microfilm, aperture cards, microfiche, and ultra fiche. Using open reels or cassettes, microfilm is often used as a way to store many documents in a small space. It has become increasingly prevalent in the development of films, as well as storage of archived newspapers. With the invention of microfilm, microfilm readers soon developed. With the increasing popularity of computers, microform has decreased in use. However, many library archives still remain in microform. Characteristics A modern microfilm reader consists of:Reference 6 *A lens that is capable of magnifying the image on the film to at least the size of the original document. * An easily replaceable light source that provides illumination without damaging the microfilm. *Minimization of light effects of the room. *A screen large enough to project the entire film image. *An e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microform
Microforms are scaled-down reproductions of documents, typically either films or paper, made for the purposes of transmission, storage, reading, and printing. Microform images are commonly reduced to about 4% or of the original document size. For special purposes, greater optical reductions may be used. Three formats are common: microfilm (reels), microfiche (flat sheets), and aperture cards. Microcards, also known as "micro-opaques", a format no longer produced, were similar to microfiche, but printed on cardboard rather than photographic film. History Using the daguerreotype process, John Benjamin Dancer was one of the first to produce microphotographs, in 1839. He achieved a reduction ratio of 160:1. Dancer refined his reduction procedures with Frederick Scott Archer's wet collodion process, developed in 1850–51, but he dismissed his decades-long work on microphotographs as a personal hobby and did not document his procedures. The idea that microphotography could be no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microfilm
Microforms are scaled-down reproductions of documents, typically either photographic film, films or paper, made for the purposes of transmission, storage, reading, and printing. Microform images are commonly reduced to about 4% or of the original document size. For special purposes, greater optical reductions may be used. Three formats are common: microfilm (reels), microfiche (flat sheets), and aperture cards. Microcards, also known as "micro-opaques", a format no longer produced, were similar to microfiche, but printed on cardboard rather than photographic film. History Using the daguerreotype process, John Benjamin Dancer was one of the first to produce microphotographs, in 1839. He achieved a reduction ratio of 160:1. Dancer refined his reduction procedures with Frederick Scott Archer's wet collodion process, developed in 1850–51, but he dismissed his decades-long work on microphotographs as a personal hobby and did not document his procedures. The idea that microphotogr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coddington Magnifier
A Coddington magnifier is a magnifying glass consisting of a single very thick lens with a central deep groove diaphragm at the '' equator'', thus limiting the rays to those close to the axis, which minimizes spherical aberration. This allows for greater magnification than a conventional magnifying glass, typically 10× up to 20×. Most single lens magnifiers are limited to 5× or so before significant distortion occurs. The drawback is that the diaphragm groove reduces the area seen through the magnifier. History In 1812 William Hyde Wollaston introduced a much improved version of the earliest magnifiers consisting of a spherical glass by employing two hemispheres of glass mounted together with a small stop between them. Sir David Brewster found that Wollaston's form worked best when the two lenses were hemispheres and the central space was filled up with a transparent cement having the same refractive index as the glass. He therefore used a sphere from a single piece of glas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations (UN) aimed at promoting world peace and security through international cooperation in education, arts, sciences and culture. It has 193 member states and 12 associate members, as well as partners in the non-governmental, intergovernmental and private sector. Headquartered at the World Heritage Centre in Paris, France, UNESCO has 53 regional field offices and 199 national commissions that facilitate its global mandate. UNESCO was founded in 1945 as the successor to the League of Nations's International Committee on Intellectual Cooperation.English summary). Its constitution establishes the agency's goals, governing structure, and operating framework. UNESCO's founding mission, which was shaped by the Second World War, is to advance peace, sustainable development and human rights by facilitating collaboration and dialogue among nations. It pursues this objectiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
