History of the camera The forerunner to the photographic camera was the camera obscura.[7] In the fifth century B.C., the Chinese philosopher Mo Ti noted that a pinhole can form an inverted and focused image, when light passes through the hole and into a dark area.[8] Mo Ti is the first recorded person to have exploited this phenomenon to trace the inverted image to create a picture.[9] Writing in the fourth century B.C., Aristotle also mentioned this principle.[10] He described observing a partial solar eclipse in 330 B.C. by seeing the image of the Sun projected through the small spaces between the leaves of a tree.[11] In the tenth century, the Arabic scholar Ibn al-Haytham (Alhazen) also wrote about observing a solar eclipse through a pinhole,[12] and he described how a sharper image could be produced by making the opening of the pinhole smaller.[11] English philosopher Roger Bacon wrote about these optical principles in his 1267 treatise Perspectiva.[11] By the fifteenth century, artists and scientists were using this phenomenon to make observations. Originally, an observer had to enter an actual room, in which a pinhole was made on one wall. On the opposite wall, the observer would view the inverted image of the outside.[13] The name camera obscura, Latin for "dark room", derives from this early implementation of the optical phenomenon.[14] The term was first coined by mathematician and astronomer Johannes Kepler in his Ad Vitellionem paralipomena of 1604.[15] The Italian scientist Giambattista della Porta described the camera obscura in detail in his 1558 work Magia Naturalis, and specifically suggested that an artist could project a camera obscura's images onto paper, and trace the outlines.[16] The camera obscura was popular as an aid for drawing and painting from the 1600s to the 1800s.[17] Portable set-ups were devised in the 17th century. For example, Kepler had built a portable tent, and outfitted the camera obscura with a lens by 1620.[18][19] This set-up remained popular up to the early 1800s.[20] The scientist Robert Hooke presented a paper in 1694 to the Royal Society, in which he described a portable camera obscura. It was a cone-shaped box which fit onto the head and shoulders of its user.[21] A hand-held device with a mirror reflex mechanism was first proposed by Johann Zahn in 1685, a design that would later be used in photographic cameras.[22] Before the development of the photographic camera, it had been known for hundreds of years that some substances, such as silver salts, darkened when exposed to sunlight.[23] In a series of experiments, published in 1727, the German scientist Johann Heinrich Schulze demonstrated that the darkening of the salts was due to light alone, and not influenced by heat or exposure to air.[24] The Swedish chemist Carl Wilhelm Scheele showed in 1777 that silver chloride was especially susceptible to darkening from light exposure, and that once darkened, it becomes insoluble in an ammonia solution.[24] The first person to use this chemistry to create images was Thomas Wedgwood.[23] To create images, Wedgwood placed items, such as leaves and insect wings, on ceramic pots coated with silver nitrate, and exposed the set-up to light. These images weren't permanent, however, as Wedgwood didn't employ a fixing mechanism. He ultimately failed at his goal of using the process to create fixed images created by a camera obscura.The first permanent photograph of a camera image was made in 1826 by Joseph Nicéphore Niépce using a sliding wooden box camera made by Charles and Vincent Chevalier in Paris.[29] Niépce had been experimenting with ways to fix the images of a camera obscura since 1816. The photograph Niépce succeeded in creating shows the view from his window. It was made using an 8-hour exposure on pewter coated with bitumen.[30] Niépce called his process "heliography".[31] Niépce corresponded with the inventor Louis-Jacques-Mande Daguerre, and the pair entered into a partnership to improve the heliographic process. Niépce had experimented further with other chemicals, to improve contrast in his heliographs. Daguerre contributed an improved camera obscura design, but the partnership ended when Niépce died in 1833.[32] Daguerre succeeded in developing a high-contrast and extremely sharp image by exposing on a plate coated with silver iodide, and exposing this plate again to mercury vapor.[33] By 1837, he was able to fix the images with a common salt solution. He called this process Daguerreotype, and tried unsuccessfully for a couple years to commercialize it. Eventually, with help of the scientist and politician François Arago, the French government acquired Daguerre's process for public release. In exchange, pensions were provided to Daguerre as well as Niépce's son, Isidore.

• published: 17 Jun 2015
• views: 5