To make the heliograph, Nipce dissolved light-sensitive bitumen in oil of lavender and applied a thin coating over a polished pewter plate. He inserted the plate into a camera obscura and positioned it near a window in his second-story workroom. After several days of exposure to sunlight, the plate yielded an impression of the courtyard, outbuildings, and trees outside. Writing about his process in December 1827, Nipce acknowledged that it required further improvements, but was nevertheless "the first uncertain step in a completely new direction."

Around 1717, Johann Heinrich Schulze captured cut-out letters on a bottle of a light-sensitive slurry, but he apparently never thought of making the results durable. Around 1800, Thomas Wedgwood made the first reliably documented, although unsuccessful attempt at capturing camera images in permanent form. His experiments did produce detailed photograms, but Wedgwood and his associate Humphry Davy found no way to fix these images.


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In 1826, Nicphore Nipce first managed to fix an image that was captured with a camera, but at least eight hours or even several days of exposure in the camera were required and the earliest results were very crude. Nipce's associate Louis Daguerre went on to develop the daguerreotype process, the first publicly announced and commercially viable photographic process. The daguerreotype required only minutes of exposure in the camera, and produced clear, finely detailed results. The details were introduced to the world in 1839, a date generally accepted as the birth year of practical photography.[2][3]The metal-based daguerreotype process soon had some competition from the paper-based calotype negative and salt print processes invented by William Henry Fox Talbot and demonstrated in 1839 soon after news about the daguerreotype reached Talbot. Subsequent innovations made photography easier and more versatile. New materials reduced the required camera exposure time from minutes to seconds, and eventually to a small fraction of a second; new photographic media were more economical, sensitive or convenient. Since the 1850s, the collodion process with its glass-based photographic plates combined the high quality known from the Daguerreotype with the multiple print options known from the calotype and was commonly used for decades. Roll films popularized casual use by amateurs. In the mid-20th century, developments made it possible for amateurs to take pictures in natural color as well as in black-and-white.

The commercial introduction of computer-based electronic digital cameras in the 1990s soon revolutionized photography. During the first decade of the 21st century, traditional film-based photochemical methods were increasingly marginalized as the practical advantages of the new technology became widely appreciated and the image quality of moderately priced digital cameras was continually improved. Especially since cameras became a standard feature on smartphones, taking pictures (and instantly publishing them online) has become a ubiquitous everyday practice around the world.

Around 1717,[12] German polymath Johann Heinrich Schulze accidentally discovered that a slurry of chalk and nitric acid into which some silver particles had been dissolved was darkened by sunlight. After experiments with threads that had created lines on the bottled substance after he placed it in direct sunlight for a while, he applied stencils of words to the bottle. The stencils produced copies of the text in dark red, almost violet characters on the surface of the otherwise whitish contents. The impressions persisted until they were erased by shaking the bottle or until overall exposure to light obliterated them. Schulze named the substance "Scotophors" when he published his findings in 1719. He thought the discovery could be applied to detect whether metals or minerals contained any silver and hoped that further experimentation by others would lead to some other useful results.[13][14] Schulze's process resembled later photogram techniques and is sometimes regarded as the very first form of photography.[15]

The early science fiction novel Giphantie[16] (1760) by the Frenchman Tiphaigne de la Roche described something quite similar to (color) photography, a process that fixes fleeting images formed by rays of light: "They coat a piece of canvas with this material, and place it in front of the object to capture. The first effect of this cloth is similar to that of a mirror, but by means of its viscous nature the prepared canvas, as is not the case with the mirror, retains a facsimile of the image. The mirror represents images faithfully, but retains none; our canvas reflects them no less faithfully, but retains them all. This impression of the image is instantaneous. The canvas is then removed and deposited in a dark place. An hour later the impression is dry, and you have a picture the more precious in that no art can imitate its truthfulness."[17] De la Roche thus imagined a process that made use of a special substance in combination with the qualities of a mirror, rather than the camera obscura. The dark place in which the pictures dried suggests that he thought about the light sensitivity of the material, but he attributed the effect to its viscous nature.

English photographer and inventor Thomas Wedgwood is believed to have been the first person to have thought of creating permanent pictures by capturing camera images on material coated with a light-sensitive chemical. He originally wanted to capture the images of a camera obscura, but found they were too faint to have an effect upon the silver nitrate solution that was recommended to him as a light-sensitive substance. Wedgwood did manage to copy painted glass plates and captured shadows on white leather, as well as on paper moistened with a silver nitrate solution. Attempts to preserve the results with their "distinct tints of brown or black, sensibly differing in intensity" failed. It is unclear when Wedgwood's experiments took place. He may have started before 1790; James Watt wrote a letter to Thomas Wedgwood's father Josiah Wedgwood to thank him "for your instructions as to the Silver Pictures, about which, when at home, I will make some experiments". This letter (now lost) is believed to have been written in 1790, 1791 or 1799. In 1802, an account by Humphry Davy detailing Wedgwood's experiments was published in an early journal of the Royal Institution with the title An Account of a Method of Copying Paintings upon Glass, and of Making Profiles, by the Agency of Light upon Nitrate of Silver. Davy added that the method could be used for objects that are partly opaque and partly transparent to create accurate representations of, for instance, "the woody fibres of leaves and the wings of insects". He also found that solar microscope images of small objects were easily captured on prepared paper. Davy, apparently unaware or forgetful of Scheele's discovery, concluded that substances should be found to eliminate (or deactivate) the unexposed particles in silver nitrate or silver chloride "to render the process as useful as it is elegant".[19] Wedgwood may have prematurely abandoned his experiments because of his frail and failing health. He died at age 34 in 1805.

French balloonist, professor and inventor Jacques Charles is believed to have captured fleeting negative photograms of silhouettes on light-sensitive paper at the start of the 19th century, prior to Wedgwood. Charles died in 1823 without having documented the process, but purportedly demonstrated it in his lectures at the Louvre. It was not publicized until Franois Arago mentioned it at his introduction of the details of the daguerreotype to the world in 1839. He later wrote that the first idea of fixing the images of the camera obscura or the solar microscope with chemical substances belonged to Charles. Later historians probably only built on Arago's information, and, much later, the unsupported year 1780 was attached to it.[24] As Arago indicated the first years of the 19th century and a date prior to the 1802 publication of Wedgwood's process, this would mean that Charles' demonstrations took place in 1800 or 1801, assuming that Arago was this accurate almost 40 years later.

Nipce died suddenly in 1833, leaving his notes to Daguerre. More interested in silver-based processes than Nipce had been, Daguerre experimented with photographing camera images directly onto a mirror-like silver-surfaced plate that had been fumed with iodine vapor, which reacted with the silver to form a coating of silver iodide. As with the bitumen process, the result appeared as a positive when it was suitably lit and viewed. Exposure times were still impractically long until Daguerre made the pivotal discovery that an invisibly slight or "latent" image produced on such a plate by a much shorter exposure could be "developed" to full visibility by mercury fumes. This brought the required exposure time down to a few minutes under optimum conditions. A strong hot solution of common salt served to stabilize or fix the image by removing the remaining silver iodide. On 7 January 1839, this first complete practical photographic process was announced at a meeting of the French Academy of Sciences,[30] and the news quickly spread.[31] At first, all details of the process were withheld and specimens were shown only at Daguerre's studio, under his close supervision, to Academy members and other distinguished guests.[32] Arrangements were made for the French government to buy the rights in exchange for pensions for Nipce's son and Daguerre and present the invention to the world (with the exception of Great Britain, where an agent for Daguerre patented it) as a free gift.[33] Complete instructions were made public on 19 August 1839.[34] Known as the daguerreotype process, it was the most common commercial process until the late 1850s when it was superseded by the collodion process. e24fc04721

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