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Cameraless Photography
A photogram is a photographic image made without a camera by placing objects directly onto the surface of a light-sensitive material such as photographic paper and then exposing it to light. The usual result is a negative shadow image that shows variations in tone that depends upon the transparency of the objects used. Areas of the paper that have received no light appear white; those exposed for a shorter time or through transparent or semi-transparent objects appear grey, while fully exposed areas are black in the final print. The technique is sometimes called cameraless photography. It was used by Man Ray in his exploration of rayographs. Other artists who have experimented with the technique include László Moholy-Nagy, Christian Schad (who called them "Schadographs"), Imogen Cunningham and Pablo Picasso. Variations of the technique have also been used for scientific purposes, in shadowgraph studies of flow in transparent media and in high-speed Schlieren photogra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photochemistry
Photochemistry is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet (wavelength from 100 to 400 nm), visible light (400–750 nm) or infrared radiation (750–2500 nm). In nature, photochemistry is of immense importance as it is the basis of photosynthesis, vision, and the formation of vitamin D with sunlight. Photochemical reactions proceed differently than temperature-driven reactions. Photochemical paths access high energy intermediates that cannot be generated thermally, thereby overcoming large activation barriers in a short period of time, and allowing reactions otherwise inaccessible by thermal processes. Photochemistry can also be destructive, as illustrated by the photodegradation of plastics. Concept Grotthuss–Draper law and Stark-Einstein law Photoexcitation is the first step in a photochemical process where the reactant is elevated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anna Atkins
Anna Atkins (née Children; 16 March 1799 – 9 June 1871) was an English botanist and photographer. She is often considered the first person to publish a book illustrated with photographic images. Some sources say that she was the first woman to create a photograph. Early life Atkins was born in Tonbridge, Kent, England in 1799. Her mother, Hester Anne Children, "didn't recover from the effects of childbirth" and died in 1800. Anna was close to her father John George Children, a renowned chemist, mineralogist, and zoologist. Anna "received an unusually scientific education for a woman of her time." Her detailed engravings of shells were used to illustrate her father's translation of Lamarck's ''Genera of Shells''. In 1825, she married John Pelly Atkins, a London West India merchant, later sheriff, and proponent of railways; during this same year, she moved to Halstead Place, the Atkins family home in Halstead, near Sevenoaks, Kent. They had no children. Atkins pursued her i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Henry Fox Talbot
William Henry Fox Talbot FRS FRSE FRAS (; 11 February 180017 September 1877) was an English scientist, inventor, and photography pioneer who invented the salted paper and calotype processes, precursors to photographic processes of the later 19th and 20th centuries. His work in the 1840s on photomechanical reproduction led to the creation of the photoglyphic engraving process, the precursor to photogravure. He was the holder of a controversial patent that affected the early development of commercial photography in Britain. He was also a noted photographer who contributed to the development of photography as an artistic medium. He published '' The Pencil of Nature'' (1844–46), which was illustrated with original salted paper prints from his calotype negatives and made some important early photographs of Oxford, Paris, Reading, and York. A polymath, Talbot was elected to the Royal Society in 1831 for his work on the integral calculus, and researched in optics, chemistry, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicéphore Niépce
Joseph Nicéphore Niépce (; 7 March 1765 – 5 July 1833), commonly known or referred to simply as Nicéphore Niépce, was a French inventor, usually credited with the invention of photography. Niépce developed heliography, a technique he used to create the world's oldest surviving product of a photographic process: a print made from a photoengraved printing plate in 1825. In 1826 or 1827, he used a primitive camera to produce the oldest surviving photograph of a real-world scene. Among Niépce's other inventions was the Pyréolophore, one of the world's first internal combustion engines, which he conceived, created, and developed with his older brother Claude Niépce. Biography Early life Niépce was born in Chalon-sur-Saône, Saône-et-Loire, where his father was a wealthy lawyer. His older brother Claude (1763–1828) was also his collaborator in research and invention, but died half-mad and destitute in England, having squandered the family wealth in pursuit of n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Negative (photography)
In photography, a negative is an image, usually on a strip or sheet of transparent plastic film, in which the lightest areas of the photographed subject appear darkest and the darkest areas appear lightest. This reversed order occurs because the extremely light-sensitive chemicals a camera film must use to capture an image quickly enough for ordinary picture-taking are darkened, rather than bleached, by exposure to light and subsequent photographic processing. In the case of color negatives, the colors are also reversed into their respective complementary colors. Typical color negatives have an overall dull orange tint due to an automatic color-masking feature that ultimately results in improved color reproduction. Negatives are normally used to make positive prints on photographic paper by projecting the negative onto the paper with a photographic enlarger or making a contact print. The paper is also darkened in proportion to its exposure to light, so a second reversal result ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in carbohydrate molecules, such as sugars and starches, which are synthesized from carbon dioxide and water – hence the name ''photosynthesis'', from the Greek ''phōs'' (), "light", and ''synthesis'' (), "putting together". Most plants, algae, and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies most of the energy necessary for life on Earth. Although photosynthesis is performed differently by different species, the process always begins when energy from light is absorbed by proteins called reaction centers that contain green chlorophyll (and other colored) pigments/chromoph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dennis Oppenheim
Dennis Oppenheim (September 6, 1938 – January 21, 2011) was an American conceptual artist, performance artist, earth artist, sculptor and photographer. Dennis Oppenheim's early artistic practice is an epistemological questioning about the nature of art, the making of art and the definition of art: a meta-art that arose when strategies of the Minimalists were expanded to focus on site and context. As well as an aesthetic agenda, the work progressed from perceptions of the physical properties of the gallery to the social and political context, largely taking the form of permanent public sculpture in the last two decades of a highly prolific career, whose diversity could exasperate his critics.Simon Taylor, ''Dennis Oppenheim, New Works'', Guild Hall Museum, East Hampton, NY: 2001. Biography and Education Oppenheim's father was a Russian immigrant and his mother a native of California. Oppenheim was born in Electric City, Washington, while his father was working as an enginee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sunburn
Sunburn is a form of radiation burn that affects living tissue, such as skin, that results from an overexposure to ultraviolet (UV) radiation, usually from the Sun. Common symptoms in humans and animals include: red or reddish skin that is hot to the touch or painful, general fatigue, and mild dizziness. Other symptoms include blistering, peeling skin, swelling, itching, and nausea. Excessive UV radiation is the leading cause of (primarily) non-malignant skin tumors,World Health Organization, International Agency for Research on Cance"Do sunscreens prevent skin cancer" Press release No. 132, 5 June 2000World Health Organization, International Agency for Research on Cance"Solar and ultraviolet radiation"IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 55, November 1997 and in extreme cases can be life-threatening. Sunburn is an inflammatory response in the tissue triggered by direct DNA damage by UV radiation. When the cells' DNA is overly damag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomas Wedgwood (photographer)
Thomas Wedgwood (14 May 1771 – 10 July 1805) was an English photographer and inventor. He is most widely known as an early experimenter in the field of photography. He is the first person known to have thought of creating permanent pictures by capturing camera images on material coated with a light-sensitive chemical. His practical experiments yielded only shadow image photograms that were not light-fast, but his conceptual breakthrough and partial success have led some historians to call him "the first photographer". Life Thomas Wedgwood was the fifth child of eight born to Josiah Wedgwood and his wife Sarah, nee Wedgwood, his third cousin. His father was the founder of the Wedgwood company. He was an uncle of the English naturalist Charles Darwin, through his sister Susannah Wedgwood who married Robert Darwin. He was born in Etruria, Staffordshire, now part of the city of Stoke-on-Trent in England. Wedgwood grew up and was educated at Etruria, and was instilled from his yo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Humphry Davy
Sir Humphry Davy, 1st Baronet, (17 December 177829 May 1829) was a British chemist and inventor who invented the Davy lamp and a very early form of arc lamp. He is also remembered for isolating, by using electricity, several elements for the first time: potassium and sodium in 1807 and calcium, strontium, barium, magnesium and boron the following year, as well as for discovering the elemental nature of chlorine and iodine. Davy also studied the forces involved in these separations, inventing the new field of electrochemistry. Davy is also credited to have been the first to discover clathrate hydrates in his lab. In 1799 he experimented with nitrous oxide and was astonished at how it made him laugh, so he nicknamed it "laughing gas" and wrote about its potential anaesthetic properties in relieving pain during surgery. Davy was a baronet, President of the Royal Society (PRS), Member of the Royal Irish Academy (MRIA), Fellow of the Geological Society (FGS), and a member ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver Chloride
Silver chloride is a chemical compound with the chemical formula Ag Cl. This white crystalline solid is well known for its low solubility in water (this behavior being reminiscent of the chlorides of Tl+ and Pb2+). Upon illumination or heating, silver chloride converts to silver (and chlorine), which is signaled by grey to black or purplish coloration to some samples. AgCl occurs naturally as a mineral chlorargyrite. Preparation Silver chloride is unusual in that, unlike most chloride salts, it has very low solubility. It is easily synthesized by metathesis: combining an aqueous solution of silver nitrate (which is soluble) with a soluble chloride salt, such as sodium chloride or cobalt(II) chloride. The silver chloride that forms will precipitate immediately. :AgNO3 + NaCl -> AgCl(v) + NaNO3 :2 AgNO3 + CoCl2 -> 2 AgCl(v) + Co(NO3)2 Structure and reactions The solid adopts the ''fcc'' NaCl structure, in which each Ag+ ion is surrounded by an octahedron of six chloride liga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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