A camera is an optical instrument used to record images. At their most basic, cameras are sealed boxes with a small hole that let light in to capture an image on a light-sensitive surface. Cameras have various mechanisms to control. Lenses focus the light entering the camera, the size of the aperture can be widened or narrowed to let more or less light into the camera, a shutter mechanism determines the amount of time the photo-sensitive surface is exposed to the light; the still image camera is the main instrument in the art of photography and captured images may be reproduced as a part of the process of photography, digital imaging, photographic printing. The similar artistic fields in the moving image camera domain are film and cinematography; the word camera comes from camera obscura, which means "dark chamber" and is the Latin name of the original device for projecting an image of external reality onto a flat surface. The modern photographic camera evolved from the camera obscura; the functioning of the camera is similar to the functioning of the human eye.

The first permanent photograph was made in 1825 by Joseph Nicéphore Niépce. A camera captures light photons from the visible spectrum for human viewing, but in general could be from other portions of the electromagnetic spectrum. All cameras use the same basic design: light enters an enclosed box through a converging or convex lens and an image is recorded on a light-sensitive medium. A shutter mechanism controls the length of time. Most cameras have a viewfinder, which shows the scene to be recorded, the ability to control focus and exposure so that it is not too bright or too dim; the aperture, sometimes called the diaphragm or iris, is the opening through which light enters the camera. Located in the lens, this opening can be widened or narrowed to control the amount of light that strikes the film; the aperture is controlled by the movements of overlapping plates or blades that rotate together and apart to shrink and expand the hole at the center. The diameter of the aperture can be set manually by adjusting a dial on the camera body or lens, or automatically based on calculations influenced by an internal light meter.

The size of the opening is set at standard increments called "f-stops", that range from f/1.4 to f/32 in standard increments: 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32. As the numbers increase, each increment halves the amount of light entering the camera. Conversely, the lower the number, the larger the opening, so the more light, let into the camera; the wider opening at the lower f-stops narrows the range of focus so the background of an image is blurry when focusing on the foreground, vice-versa. This "depth of field" increases as the aperture closes, so that objects that are at differing distances from the camera can both be in focus; the shutter, along with the aperture, is one of two ways to control the amount of light entering the camera. The shutter determines the duration; the shutter is opened, light enters the camera and exposes the film or sensor to light, the shutter closes. There are two types of mechanical shutters; the leaf-type uses a circular iris diaphragm maintained under spring tension inside or just behind the lens that opens and closes when the shutter is released.

More a focal-plane shutter is used. This shutter operates close to the film plane and employs metal plates or cloth curtains with an opening that passes across the light-sensitive surface; the curtains or plates have an opening, pulled across the film plane during an exposure. The focal-plane shutter is used in single-lens reflex cameras, since covering the film rather than blocking the light passing through the lens allows the photographer to view through the image through the lens at all times except during the exposure itself. Covering the film facilitates removing the lens from a loaded camera. Digital cameras may use one of these types of mechanical shutters or they may use an electronic shutter, the type used in the cameras of smartphones. Electronic shutters either record data from the entire sensor at the same time or record the data line by line across the sensor. In movie cameras, a rotary shutter opens and closes in sync with the advancing of each frame of film; the duration is called the shutter exposure time.

The longer the shutter speed, the slower it is. Typical exposure times can range from one second to 1/1,000 of a second, though durations longer and shorter than this are not uncommon. In the early stages of photography, exposures were several minutes long; these long exposure times result in blurry images, as a single object is recorded in multiple places across a single image for the duration of the exposure. To prevent this, shorter exposure times can be used. Short exposure times can capture fast-moving action and eliminate motion blur. Like aperture settings, exposure times increment in powers of two; the two settings determine the exposure value, a measure of how much light is recorded during the exposure. There is a direct relationship between the exposure times and aperture settings so that if the exposure time is lengthened one step, but the aperture opening is narrowed one step, the amount of light exposi

Akkad (city)

Akkad was the name of a Mesopotamian city and its surrounding area. Akkad was the capital of the Akkadian Empire, the dominant political force in Mesopotamia during a period of about 150 years in the last third of the 3rd millennium BC, its location is unknown, although there are a number of candidate sites situated east of the Tigris between the modern cities of Samarra and Baghdad. Before the decipherment of cuneiform in the 19th century, the city was known only from a single reference in Genesis 10:10 where it is written אַכַּד, rendered in the KJV as Accad; the name is given in a list of cities of Nimrod in Sumer. Sallaberger and Westenholz cite the number of 160 known mentions of the city in the extant cuneiform corpus, in sources ranging in date from the Old Akkadian period itself down to the Neo-Babylonian period; the name is spelled logographically as URIKI, or phonetically as a-ga-dèKI, variously transcribed into English as Akkad, Akkade or Agade. The etymology of the name is unclear, but not of Akkadian origin.

Various suggestions have proposed Sumerian, Lullubean etymologies. The non-Akkadian origin of the city's name suggests that the site may have been occupied in pre-Sargonic times, as suggested by the mentioning of the city in one pre-Sargonic year-name; the inscription on the Bassetki Statue records that the inhabitants of Akkad built a temple for Naram-Sin after he had crushed a revolt against his rule. The main goddess of Akkad was Ishtar-Astarte, called ‘Aštar-annunîtum or "Warlike Ishtar", her husband Ilaba was revered in Akkad. Ishtar and Ilaba were worshipped at Sippar in the Old Babylonian period because Akkad itself had been destroyed by that time; the city was in ruins by the mid-first millennium BC. Many older proposals put Akkad on the Euphrates, but more recent discussions conclude that a location on the Tigris is more likely; the identification of Akkad with Sippar ša Annunîtum, along a canal opposite Sippar ša Šamaš was rejected by Unger based on a Neo-Babylonian text that lists Sippar ša Annunîtum and Akkad as separate places.

Harvey Weiss proposed a large site 5 kilometres northwest from Kish. Excavations have shown that the remains at Ishan Mizyad date to the Ur III period and not to the Akkadian period. Discussion since the 1990s has focused on sites east of the Tigris. Wall-Romana suggested a location near the confluence of the Diyala River with the Tigris, more Tell Muhammad in the south-eastern suburbs of Baghdad as the likeliest candidate for Akkad, although admitting that no remains datable to the Akkadian period had been found at the site. Sallaberger and Westenholz suggested a location close to the confluence of the ʿAdhaim river east of Samarra. Reade suggested a site in this vicinity, by Qādisiyyah, based on a fragment of an Old Akkadian statue found there; this had been suggested much earlier by Lane. Based on an Old Babylonian period itinerary from Mari, Akkad would be on the Tigris just downstream of the current city of Baghdad. Mari documents indicate that Akkad is sited at a river crossing. Cities of the Ancient Near East History of Mesopotamia Foster, Benjamin R. "Akkad", in Bagnall, Roger S.

The Encyclopedia of Ancient History, Chicago: Blackwell, pp. 266–267, doi:10.1002/9781444338386.wbeah01005 Meador, Betty De Shong, Lady of the Largest Heart. Poems by the Sumerian High Priestess Enheduanna, Austin: University of Texas Press, ISBN 978-0-292-75242-9 Pruß, Alexander, "Remarks on the Chronological Periods", in Lebeau, Marc. 3000–323 BC. Second Edition, Blackwell History of the Ancient World, Malden: Blackwell, ISBN 9781405149112 Wall-Romana, Christophe, "An Areal Location of Agade", Journal of Near Eastern Studies, 49: 205–245, doi:10.1086/373442, JSTOR 546244 Weiss, Harvey, "Kish and Agade", Journal of the American Oriental Society, 95: 434–453, doi:10.2307/599355, JSTOR 599355

National University of Saint Augustine

The National University of Saint Agustine, known locally as Universidad Nacional de San Agustín is a state-owned university in Arequipa, Peru. The UNSA is one of the oldest public universities in Peru and it has been in continuous operation since its founding on November 11, 1828; the National University of Saint Agustine has been ranked as one of the top public schools in Peru. The university comprises three campuses, 17 colleges, 45 professional schools from the fields of humanities, natural sciences, social sciences and engineering. Arequipa's principal stadium — one of the largest in Peru, Estadio de la UNSA — was built by the university. Official website List of universities in Peru "Universidad Nacional de San Agustín de Arequipa -History and general reference". Official university site. Archived from the original on December 16, 2004. Retrieved May 27, 2005. Universidad Nacional de San Agustín de Arequipa website