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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| History of photography | 3/7 | https://en.wikipedia.org/wiki/History_of_photography | reference | science, encyclopedia | 2026-05-05T06:41:03.827937+00:00 | kb-cron |
=== Thomas Wedgwood and Humphry Davy: Fleeting detailed photograms (1790–1802) === 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". Wedgwood may have prematurely abandoned his experiments because of his frail and failing health. He died at age 34 in 1805. Davy seems not to have continued the experiments. Although the journal of the nascent Royal Institution probably reached its very small group of members, the article must have been read eventually by many more people. It was reviewed by David Brewster in the Edinburgh Magazine in December 1802, appeared in chemistry textbooks as early as 1803, was translated into French and was published in German in 1811. Readers of the article may have been discouraged to find a fixer, because the highly acclaimed scientist Davy had already tried and failed. Apparently the article was not noted by Niépce or Daguerre, and by Talbot only after he had developed his own processes.
=== Jacques Charles: Fleeting silhouette photograms (circa 1801) === 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 François 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. 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.
== 1816 to 1833: Niépce's earliest fixed images ==
Nicéphore Niépce was a French aristocrat, scientist, and chemist. His family fortune allowed him to engage in inventions and scientific research. In 1816, using paper coated with silver chloride, he succeeded in photographing the images formed in a small camera, but the photographs were negatives, darkest where the camera image was lightest and vice versa, and they were not permanent in the sense of being reasonably light-fast; like earlier experimenters, Niépce could find no way to prevent the coating from darkening all over when it was exposed to light for viewing. Disenchanted with silver salts, he turned his attention to light-sensitive organic substances. The oldest surviving photograph of the image formed in a camera was created by Niépce in 1826 or 1827. It was made on a polished sheet of pewter and the light-sensitive substance was a thin coating of bitumen, a naturally occurring petroleum tar, which was dissolved in lavender oil, applied to the surface of the pewter and allowed to dry before use. After a very long exposure in the camera (traditionally said to be eight hours, but now believed to be several days), the bitumen was sufficiently hardened in proportion to its exposure to light that the unhardened part could be removed with a solvent, leaving a positive image with the light areas represented by hardened bitumen and the dark areas by bare pewter. To see the image plainly, the plate had to be lit and viewed in such a way that the bare metal appeared dark and the bitumen relatively light. In partnership, Niépce in Chalon-sur-Saône and Louis Daguerre in Paris refined the bitumen process, substituting a more sensitive resin and a very different post-exposure treatment that yielded higher-quality and more easily viewed images. Exposure times in the camera, although substantially reduced, were still measured in hours.
== 1832 to 1840: Early monochrome processes ==