Sehnsucht - An Art Project

SEHNSUCHT

An art project on the psychological state during the lockdown

			workshop
Glossary

Technical term

Camera obscura	A camera obscura (Latin for 'dark chamber') is a dark space with a small opening, through which the light from outside enters to form a projected image onto a screen inside. A bright or strongly lit object for instance, would then be seen on the screen, appearing rotated and reversed when it is viewed from the direction of the light source. This projection preserves the colours and intensity of the light. A pinhole camera or a darkened room with a small aperture are common examples of camera obscura.

Dunkelfeldprinzip	Sir John Herschel discovered in 1839 that an underexposed glass negative appears positive when it is viewed against a black background. The developed silver shows itself as white, reflecting the light from a certain angle, while transparent areas without silver appear black.	Work by Claus Dieter Geissler

Vignetting	Vignetting is often an unintended phenomenon, which shows the periphery of the image darker than its centre in the shape of an arc. It can be caused by an improper setting or a faulty construction of the camera as well as an inadequate use of the lens, filters or lens hoods. The effect normally shows a gradual decrease of the intensity of light toward the edge of an image. Occasionally, it is favoured by some portraiture or landscape photographers, who deliberately apply the effect to emphasizes the centre of the image.	Work by Patti Rose Rocha

Historical process

Heliography	Heliography was invented by Joseph Nicéphore Niépce ca. 1822. He applied a known characteristic of bitumen used in lithography, that it hardens when it comes in contact with light. Using a camera obscura, he succeeded in capturing the trace of the light; an image onto a prepared plate. His work, View from the Window at Le Gras from 1826 is regarded as the oldest existing photograph.

Daguerreotype	Louis-Jacques-Mandé Daguerre invented the daguerreotype process in the 1830s, making it public in 1839. It was used widely in the 1840s and early 1850s, while it was eventually replaced with the introduction of the wet plate collodion process. Daguerreotypes reveal sharp and fine details, and the relatively short exposure times required made the process suitable for portraiture. Each unique plate has a fragile surface and is laterally reversed. The image appears positive or negative depending on the viewing angle.

Calotype	Calotype was the negative process patented by William Henry Fox Talbot in 1841, using light sensitive emulsion coated onto a paper base. The developed paper negative then enabled the production of numerous positive prints, being an advantage over the Daguerreo-type. However, the paper negative could not retain sharp details and the negative’s paper structure was visible on the positive image.

Cyanotype	Sir John Hershel discovered the Cyanotype in 1842, which became a popular process in Victorian England. The process, with its typical Prussian blue colour, was widely used as ‘blueprints’ by architects and engineers until the 1940s. A solution of ferric ammonium citrate and potassium ferricyanide is mixed and applied onto paper. The dried surface of the material is exposure to ultra violet light (i.e. the sun) and then rinsed in water. A negative (contact print) or an object (photogram) can be used to create an image.	Work by Lluís Estopiñan

Wet collodion process	Frederick Scott Archer invented the wet collodion process in the late 1840s using a silver solution coated onto glass plate prepared with collodion. He published his discovery and formula in The Chemist in March 1851. A year later, together with Peter Wickens Fry, he developed the glass negative plate to a positive image, applying the Dunkelfeldprinzip. He also published The Manual of the Collodion Photographic Process in 1852. The wet collodion process replaced the Daguerreotype and became popular in the second half of the 19th century. The plate is coated with iodized collodion, then bathed in a silver nitrate solution for a few minutes. The plate must be exposed while it is still wet, then developed, fixed, washed and dried.
— Ambrotype	James Ambrose Cutting patented the ambrotype in 1854 in USA. This was a direct positive process, which showed an unreversed image behind the glass.
— Tintype (Ferrotype)	The tintype (or ferrotype) was a similar process also applying the Dunkelfeldprinzip. Instead of glass, it used a thin metal plate, coated with black lacquer as a background. Since the metal plate was used instead of glass, it was less expensive and easier to handle. Patented by Hamilton L. Smith in 1856.	Work by Claus Dieter Geissler

Platinotype	The Platinotype was developed by William Willis in 1873, and became popular among the Pictorialists. With the rising price of platinum due to the First World War, palladium was found to be a working substitute delivering similar results. Platinum/palladium printing is a contact process. Exposure to UV light converts ferric oxalate to ferrous oxalate, reacting with platinum or palladium to build the image. The metal lies directly on the paper, slightly absorbed, but without a gelatin or albumen emulsion coating the paper. This leads to a more diffuse and less reflective print. Platinum is chemically more stable than the silver or gold.	Work by Patti Rose Rocha

Modern and experimental process

Silver gelatin print	Richard Leach Maddox introduced the silver gelatin process as early as 1871 and it was later refined by Charles Harper Bennett in 1878. With further improvements made to ‘developing out’ paper from 1880s to 1890s, such as the introduction of a baryta coating in 1894, silver gelatin established itself as the most common monochrome photographic printing process of the 20th century.	Work by Joan Teixidor

Chromogenic print	Chromogenic print refers to a colour photographic print made from a colour negative, transparency or digital devices. The paper has three layers of gelatin containing subtractive colour dye couplers, which build the image. The term C-print derives from Kodak paper „Type C“ introduced in 1955, but is also widely used for the chromogenic prints made from negatives. The prints mede from the digital files are generally called after the applied exposing device such as Lambda or LightJet.	Work by Jeanne Grouet

Lith print	Lith printing is an alternative black and white printing process with a characteristic harsh contrast, formed by development in an extremely diluted ‘lith’ developer. Results are governed by the choice of suitable photographic papers, length of print exposure, processing time and the dilution and temperature of the developer. In addition, the use of additives or toners will provide unique printing results.	Work by Hiro Matsuoka

Film soup	Film soup is an experimental method that influences the chemical reactions in the film developing process by deliberately soaking the film (or a disposable camera) in a liquid such as tea, juice, milk, wine or detergent. This can be for several hours or days, depending on the dilution of the liquid and desired result. The film will then be rinsed in clear water and developed conventionally.	Work by Juliana Gagné
		Workshop by Juliana Gagné

Photo object	Any surface, which accepts a coating of photographic emulsion, can be made into a photographic object. Traditionally, glass, metal and paper are common materials used with light sensitive emulsions. The surfaces do not have to be smooth or flat to receive the emulsion, but must be able to adhere throughout the developing process, including the required washing time.	Work by Hiro Matsuoka