Photography was not invented overnight – it developed comparatively slowly as people in several countries improved their different processes. The sensitivity of silver salts to light had been investigated, from a purely technical point of view, as early as the eighteenth century by Johann Schulze in Germany, Jean Senebier in Switzerland and William Lewis in England.. Later, Thomas Wedgewood, son of the famous English potter Josiah Wedgewood, succeeded in producing short-lived impressions of plants and other objects which he placed directly onto leather or paper sensitized by silver nitrate.
Nicéphore Niépce solved the problem of fixing an image on a "heliographic plate" in 1825, and in 1827 began working with Louis Jacques Mandé Daguerre to improve a process that became known as “heliography”. However, Niépce died in 1833 leaving his partner to continue the research alone. Daguerre was the Director of the Diorama (a popular Parisian light show), and was consequently familiar with the camera obscura. This instrument was essentially a dark box with a single small aperture to admit light. An image of a subject appropriately placed outside the box was then focused onto the inside surface opposite the aperture, and used as an aid to accurate drawing. Daguerre was fascinated by the clarity of the images this instrument produced, and wanted to fix them directly without the need for manual intervention.
It was not until 1837 that he perfected a process that recorded camera obscura images in great detail. He used a copper plate sensitized with bitumen of Judea, and developed the image using mercury vapour. This became known as the "daguerreotype" process. However, Daguerre failed to market his idea and so sought official backing. His secrets were eventually handed over to the French State in return for an annual pension for life. Almost immediately, in August 1839, the details of the daguerreotype process were revealed to the world and "photography", as it was first called by Sir John Herschel, was born.
There followed an explosion of interest in this "magic" new invention. Demonstrations of "daguerreotyping" were given in the streets of Paris and use of the process soon spread throughout Europe and into the United States. Every enthusiast wanted to record local scenes, but the equipment required was cumbersome and prohibitively expensive. The success of the daguerreotype eclipsed every other rival process, but in 1840 William Henry Fox Talbot, an English scientist trained at Cambridge University, developed a “photogenic drawing” process that represented an important step forward. Starting with a negative image from a camera obscura, he developed a successful negative-to-positive process that made it possible to produce numerous positive prints of the same image. His invention, which became known as the "calotype", was protected by the granting of several patents in 1841.
One of the principal problems of the daguerreotype was the exposure time. In 1838, according to Daguerre, exposure times of up to two hours could be required. These reduced rapidly as development gathered pace, and by 1840 exposures of only 10 seconds made portraiture possible. The first commercial portrait studios opened in the US in 1840 and in London and Paris a short time later. By 1853 there were more than one hundred daguerreotype studios in existence.
Fox Talbot's calotype process was limited by the same requirement for long exposures, although he had reduced them to less than one minute by 1841. However, less rapid development ultimately led to the commercial failure of the calotype portrait, and consequently restricted use of the process to still-life and outdoor photography. It was particularly popular with travellers because its paper base made it lighter and more readily transportable than the heavy copper plates required for daguerreotypes. Calotypes also became well established in France, and several groups of enthusiasts produced notable collections of images. Some of their images were exhibited at the Great Exhibition in London in 1851, where a new technique based upon a glass negatives coated with collodion also gained recognition. The use of a smooth glass plate helped to produce a clear image with no grain. The combination of low exposure times, excellent clarity and the ability to make multiple prints, more or less guaranteed success for the collodion process. Indeed, from 1855 until the late 1870's it was used, in conjunction with an albumen-coated paper printing technique, as the principal photographic method.