Photography

The word photography derives from the Greek words 'photos' - meaning light and 'graphein' - to write. The word was popularised by Sir John Herschel in 1839. Modern photography began in the 1820s with the first permanent photographs.

A camera obscura box used for drawing images
Photography is the result of combining several technical discoveries. Long before the first photographs were made, Chinese philosopher Mo Ti and Greek philosophers such as Aristotle and Euclid described a pinhole camera in the 5th and 4th centuries B.C.E,[2][3] Ibn al-Haytham (Alhazen) (965–1040) studied the camera obscura and pinhole camera,[3][4] Albertus Magnus (1193/1206-1280) discovered silver nitrate, and Georges Fabricius (1516-1571) discovered silver chloride. Daniel Barbaro described a diaphragm in 1568. Wilhelm Homberg described how light darkened some chemicals (photochemical effect) in 1694. The novel Giphantie (by the French Tiphaigne de la Roche, 1729-1774) described what can be interpreted as photography.
For years images have been projected onto surfaces. According to the Hockney–Falco thesis as argued by artist David Hockney,[5] some artists used the camera obscura and camera lucida to trace scenes as early as the 16th century. However, this theory is heavily disputed by today's contemporary realist artists who are able to create high levels of realism without optical aids.[6] These early cameras did not record an image, but only projected images from an opening in the wall of a darkened room onto a surface, turning the room into a large pinhole camera. The phrase camera obscura literally means dark chamber. While this early prototype of today's modern camera may have had modest usage in its time, it was an important step in the evolution of the invention.

Development of chemical photography
The first permanent photograph was an image produced in 1825 by the French inventor Joseph Nicéphore Niépce. His photographs were produced on a polished pewter plate covered with a petroleum derivative called bitumen of Judea. Bitumen hardens with exposure to light. The unhardened material may then be washed away and the metal plate polished, rendering a negative image which then may be coated with ink and impressed upon paper, producing a print. Niépce then began experimenting with silver compounds based on a Johann Heinrich Schultz discovery in 1724 that a silver and chalk mixture darkens when exposed to light.
In partnership, Niépce (in Chalon-sur-Saône) and Louis Daguerre (in Paris) refined the existing silver process.[7] In 1833 Niépce died of a stroke, leaving his notes to Daguerre. While he had no scientific background, Daguerre made two pivotal contributions to the process. He discovered that exposing the silver first to iodine vapour before exposure to light, and then to mercury fumes after the photograph was taken, could form a latent image. Bathing the plate in a salt bath then fixes the image. On January 7, 1839 Daguerre announced that he had invented a process using silver on a copper plate called the daguerreotype.[8] The French government bought the patent and immediately made it public domain.
In 1832, French-Brazilian painter and inventor Hercules Florence had already created a very similar process, naming it Photographie.
After reading about Daguerre's invention, Fox Talbot worked on perfecting his own process; in 1839 he got a key improvement, an effective fixer, from John Herschel, the astronomer, who had previously showed that hyposulfite of soda (also known as hypo, or now sodium thiosulfate) would dissolve silver salts. Later that year, Herschel made the first glass negative.
By 1840, Talbot had invented the calotype process. He coated paper sheets with silver chloride to create an intermediate negative image. Unlike a daguerreotype, a calotype negative could be used to reproduce positive prints, like most chemical films do today. Talbot patented[9] this process, which greatly limited its adoption. He spent the rest of his life in lawsuits defending the patent until he gave up on photography. Later George Eastman refined Talbot's process, which is the basic technology used by chemical film cameras today. Hippolyte Bayard had also developed a method of photography but delayed announcing it, and so was not recognized as its inventor.
In 1851 Frederick Scott Archer invented the collodion process.[citation needed] Photographer and children's author Lewis Carroll used this process.[citation needed]
Slovene Janez Puhar invented the technical procedure for making photographs on glass in 1841.[citation needed] The invention was recognized on July 17, 1852 in Paris by the Académie Nationale Agricole, Manufacturière et Commerciale.

Roger Fenton's assistant seated on Fenton's photographic van, Crimea, 1855.
Herbert Bowyer Berkeley experimented with his own version of collodian emulsions after Samman introduced the idea of adding dithionite to the pyrogallol developer.[citation needed] Berkeley discovered that with his own addition of sulfite, to absorb the sulfur dioxide given off by the chemical dithionite in the developer, that dithionite was not required in the developing process. In 1881 he published his discovery. Berkeley's formula contained pyrogallol, sulfite and citric acid. Ammonia was added just before use to make the formula alkaline. The new formula was sold by the Platinotype Company in London as Sulpho-Pyrogallol Developer.[10]
Nineteenth-century experimentation with photographic processes frequently became proprietary. The German-born, New Orleans photographer Theodore Lilienthal successfully sought legal redress in an 1881 infringement case involving his "Lambert Process" in the Eastern District of Louisiana.