How it began
 
 
 

 

 

The foundations of an art: a prehistory of photography

The word photography means ‘writing with light’, and was first used by Sir John Herschel in 1839. This was the year that the invention of photography was made public. However, there were hundreds of years of research and experiments before this time…

The History of the Camera Obscura

Camera obscura: a dark room with a tiny hole in the wall or the roof, through which the view outside is projected onto the opposite wall or a screen.

The first person to observe the optical principles of the camera obscura was Aristotle (384-322 BC), when he observed a crescent-shaped partial eclipse of the sun, projected on the ground through the holes of a strainer. The actual invention of the camera obscura has been erroneously accredited by different writers to Roger Bacon, Leonardo da Vinci, G.B. Della Porta and Alberti. However, in the tenth century (250 years prior to Bacon) an Arabic scholar, known as Alhazen, described the camera obscura. Girolama Cardano, one of the great intellectuals of the renaissance, was the first person to describe the camera obscura used in conjunction with a bi-convex lens. This increased the sharpness of the projected image, but reduced its brightness. Della Porta was the first who used a concave mirror to increase the size of the image and also to erect the image (images from camera obscura had previously been small and upside down). He was also the first to suggest the use of the camera obscura as an artistic tool, so that people who could not paint could use the projected image to ‘trace’ the outlines of their picture, and add the paint later.

Friedrich Risner first suggested a portable camera obscura, presumably for its use as an artistic aid. He suggested the use of a lightweight wooden hut, with a small hole and lens in each wall, and a cube of paper in the centre for drawing. Sir Henry Wotton first describes a tent camera obscura, used by astronomer Johann Kepler in 1620. However, the earliest reference to a small portable box camera came in 1657, from Kasper Schott. This concept was advanced in 1676 by Johann Christoph Sturm, who described and illustrated the first portable reflex camera obscura, used as an aid to drawing and painting. By the beginning of the eighteenth century, there became a craze for camera obscuras in different shapes and forms. Described by John Harris as ‘one of the finest sights in the world’, the camera obscura was now widely used by artists and scientists alike, as well as for recreational and entertainment purposes, as mentioned in contemporary literature.

The History of Photochemistry

A substance which undergoes physical or chemical changes when subjected to light energy is called a photochemical substance.

Harnessing the light energy of an optical image and producing a permanent picture is the basis of modern photography. However, recognising the photochemical properties of substances took quite some time. A common fallacy is that the blackening of silver salts by light was known to the alchemists of the Middle Ages and renaissance. The truth is that Albertus Magnus said that silver nitrate blackens human skin, and is very hard to remove. He did not mention anything about light. Georgius Agricola never mentioned silver salts at all. Georgius Fabricius described the texture and colour of silver chloride, but did not mention its photochemical properties. Angelo Sala, in 1614, noticed that powdered silver nitrate turns black upon exposure to the sun. However, over 100 years later, Johann Schulze was the first person to attribute this change solely to light, and not heat.

The Foundations of Modern Photography

The concept of combining the camera obscura with photosensitive chemicals occurred sometime in the late 1790’s, the man responsible being Thomas Wedgwood. However, he was unsuccessful in doing this, probably due to the fact that he did not expose the image onto the photochemicals for long enough. Success did strike in 1802, when he and his friend Sir Humphry Davy produced ‘shadow images’. These were accomplished by placing objects (leaves and feathers) on paper and leather soaked in photosensitive chemicals, and exposing them to sunlight. Unfortunately, they were unable to fix these images, and they were soon blackened when viewed in the light.

In 1826, Joseph Nicephore Niepce succeeded in obtaining a record of view. He did this by coating a metal plate in asphaltum and, after exposing the plate to an image through a camera, treating it with aromatic oils and using it as a printing plate. The first ‘photograph’ is very crude, and probably needed a whole day’s exposure.

Niepce was unhappy with the impracticality of the process, and spent much time trying to improve it. In 1829, he began to work with another scientist, Louis Jacques Mande Daguerre. Niepce died in 1833, and when he did, Daguerre stopped using asphaltum and began using silver salts as the photosensitive medium. 6 years later, in 1839, he announced the ‘Daguerreotype process’. This was the first photographic process, consisting of a silvered copper plate exposed to iodine vapour to produce a coating of silver iodide. The plate was then exposed to the image, but the image did not appear. Instead, mercury vapour was condensed onto the plate and the image was revealed. The Daguerreotype provided a direct positive image, and provoked a great deal of interest. However, because these Daguerreotype images were ‘one off’ (only one image could be produced from each picture taken), interest soon dwindled, and instead turned towards a technique that could produce multiple images from one camera shot. Hence, the negative was born…

The Calotype Process

The calotype process was invented by William Henry Fox Talbot, and was the first positive/negative process. Fox Talbot soaked paper in a solution of sodium chloride, then in a solution of silver nitrate, which formed silver chloride on the paper. It was repeated several times to increase the concentration of the chemicals in the paper, and the paper was then exposed wet. By exposing it wet, and with so much chemicals on it, the exposure time required to darken the paper sufficiently was cut from an hour to ten minutes. Once exposed, the image was fixed with either potassium iodide or sodium chloride. In 1835, he produced what is thought to be his first successful negative on paper.


After further experiments over the forthcoming years, Fox Talbot discovered the invisible latent image and its development with chemicals. He began coating his negative paper with wax, making it more translucent, and was able to produce positive images by projecting the negative image onto a similar material. The essential principles of modern black and white photography are the same as those of the calotype process. However, the process has evolved, and has become much more efficient.

To find out more about the history of photography from 1839 onwards, please visit one of the following links:

http://www.rleggat.com/photohistory/index.html

http://www.photographymuseum.com/

http://www.primenet.com/~sos/photopage.html