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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 1790s, 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 days 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
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