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The origins of photography go back to a contraption called a camera obscura. The name comes from the Latin for darkened chamber and is a box or a room with a small hole in one of its side walls. Light from a scene outside shines through this hole and strikes the opposite inside surface, on which an inverted, or upside down, version of the scene appears (see diagram). In the early science of optics this provided proof that light travelled in a straight line. As you can see in the picture, it was also used as a drawing aid by artists, who could simply trace the image onto paper and then turn it the right way up. The first clear description of a camera obscura was by the famous artists Leonardo da Vinci, who used one himself, in his Codex Antlanticus in 1502.
This image-inversion through a small opening remained the principle behind film cameras until they were largely replaced by digital ones in the mid 1990s. The other element was of course the film itself, which on a basic level is just a surface coated with photosensitive chemicals, which means that they react to light. These had been discovered as early as the 12th century by a German friar called Albertus Magnus, who discovered that silver nitrate darkened when exposed to light. However, it was only in the 19th century that anyone thought to bring the two concepts together.
The first known attempt to capture the image in a camera obscura was by Thomas Wedgewood in 1800. He used paper or white leather treated with silver nitrate, but found that the image from a camera obscura was too faint to have an effect on the photochemical. However, he did manage to capture the shadows of objects placed directly on the surface of the paper if it was placed in direct sunlight. The resulting images are called photograms, and continue to be produced by artists today. Sadly Wedgewood was unable to ‘fix’ his images, and prevent them from fading over time, so we don’t have any record of these early photographic attempts.
In 1816 Joseph Nicéphore Niépce managed to capture the images in a small camera obscura for the first time, using paper coated in silver chloride, another photosensitive chemical. These images were negatives, so were lightest where the projected scene was darkest and vice versa, and like Wedgewood’s would fade overtime. However, Niépce went on to invent heliography in 1822, meaning ‘sun drawing’, and therefore made the world’s first permanent photographic image. Heliography used an asphalt called Bitumen of Judea, which was used by artists to make etchings, and which became less soluble when exposed to light. By placing an engraving or drawing onto a sheet of metal or glass which had been coated in the Bitumen and leaving it in the sun, Niépce managed to create the world’s first photocopy.
Luckily, Niépce didn’t stop there but continued to experiment with the camera obscura. Using a pewter plate coated in Bitumen, he managed to take the first camera photograph in 1827 (pictured). You might be able to make out in the image that the sun light has illuminated the buildings on both sides of the images. This is because the camera took at least eight hours of exposure to produce an image, which was a severely limiting factor in early photography.