Photography
Photography (derived
from the Greek phot- for
"light" and -graphos for "drawing") is the art, science, and practice of
creating durable images by
recording light or other electromagnetic radiation, either chemically by means of a light-sensitive material such as photographic film, or
electronically by means of an image sensor. Typically, a lens is used to focus the light reflected or emitted from objects into
a real image on the
light-sensitive surface inside a camera during a timed exposure. The result in an electronic image sensor is an electrical charge at each pixel, which is electronically processed and stored
in a digital image file for subsequent display or processing. The result in a photographic emulsion is an invisible latent image, which is later
chemically developed into a visible image, either negative or positive depending on the purpose of the photographic material and the method
of processing. A negative image on film is traditionally used to photographically create
a positive image on a paper base, known as a print, either by using
an enlarger or by contact printing. Photography has many uses
for business, science, manufacturing (e.g. photolithography), art, recreational purposes,
and mass communication.
First camera photography (1820s)
Invented in the first decades of the
19th century, photography (by way of the camera) seemed able to capture more
detail and information than traditional mediums, such as painting and
sculpting. Photography as a usable process goes back to the 1820s with the
development of chemical photography. The first permanent photoetching was an image produced in 1822 by the French inventor Nicéphore Niépce, but it was destroyed by a later attempt to
duplicate it Niépce was
successful again in 1825. He made the first permanent photograph from nature
(his View
from the Window at Le Gras) with
a camera obscura in 1826. Because his photographs took so long to expose (eight hours), he sought to find a new process.
Working in conjunction with Louis Daguerre, they experimented with silver compounds based on
a Johann Heinrich
Schultz discovery
in 1816 that a silver and chalk mixture darkens when exposed to light. Niépce
died in 1833, but Daguerre continued the work, eventually culminating with the
development of thedaguerreotype in 1837. Daguerre took the first ever photo of a
person in 1838 when, while taking a daguerreotype of a Paris street, a
pedestrian stopped for a shoe shine, long enough to be captured by the long
exposure (several minutes). Eventually, France agreed to pay Daguerre a pension
for his formula, in exchange for his promise to announce his discovery to the
world as the gift of France, which he did in 1839.
Black-and-white
All photography was originally
monochrome, or black-and-white. Even after color film was readily available,
black-and-white photography continued to dominate for decades, due to its lower
cost and its "classic" photographic look. It is important to note that
some monochromatic pictures are not always pure blacks and whites, but also
contain other hues depending on the process. The cyanotype process produces an
image composed of blue tones. The albumen process, first used more than 150
years ago, produces brown tones.
Many photographers continue to produce
some monochrome images, often because of the established archival permanence of
well processed silver halide based materials. Some full color digital images
are processed using a variety of techniques to create black and whites, and
some manufacturers produce digital cameras that exclusively shoot monochrome.
Color
Color photography was explored beginning in the mid-19th century.
Early experiments in color required extremely long exposures (hours or days for
camera images) and could not "fix" the photograph to prevent the
color from quickly fading when exposed to white light.
The first permanent color photograph
was taken in 1861 using the three-color-separation principle first published by
physicist James Clerk Maxwell in 1855. Maxwell's idea was to take three separate
black-and-white photographs through red, green and blue filters. This provides the photographer with the three basic channels required to recreate
a color image.
Transparent prints of the images could
be projected through similar color filters and superimposed on the projection
screen, an additive method of color reproduction. A color print on paper could
be produced by superimposing carbon prints of the three images made in their complementary colors, a subtractive method of color reproduction pioneered by Louis Ducos du
Hauron in
the late 1860s.
Russian photographer Sergei
Mikhailovich Prokudin-Gorskii made
extensive use of this color separation technique, employing a special camera
which successively exposed the three color-filtered images on different parts
of an oblong plate. Because his exposures were not simultaneous,
unsteady subjects exhibited color "fringes" or, if rapidly moving
through the scene, appeared as brightly colored ghosts in the resulting
projected or printed images.
The development of color photography
was hindered by the limited sensitivity of early photographic materials, which
were mostly sensitive to blue, only slightly sensitive to green, and virtually
insensitive to red. The discovery of dye sensitization by photochemist Hermann Vogel in 1873 suddenly made it possible to add
sensitivity to green, yellow and even red. Improved color sensitizers and
ongoing improvements in the overall sensitivity of emulsions steadily reduced the once-prohibitive long exposure
times required for color, bringing it ever closer to commercial viability.
Autochrome, the first commercially successful color process,
was introduced by the Lumière
brothers in 1907.
Autochrome plates incorporated a mosaic color filter layer made of dyed grains of potato starch, which allowed the three color components to be
recorded as adjacent microscopic image fragments. After an Autochrome plate was reversal processed to produce a positive transparency, the starch grains served to illuminate each
fragment with the correct color and the tiny colored points blended together in
the eye, synthesizing the color of the subject by the additive method. Autochrome plates were one of several varieties
of additive color screen plates and films marketed between the 1890s and the
1950s.
Kodachrome, the first modern "integral tripack" (or
"monopack") color film, was introduced by Kodak in 1935. It captured the three color components in
a multilayeremulsion. One layer was sensitized to record the
red-dominated part of the spectrum,
another layer recorded only the green part and a third recorded only the blue.
Without special film processing, the result would simply be three superimposed
black-and-white images, but complementary cyan, magenta, and yellow dye images were created
in those layers by adding color couplers during a complex processing procedure.
Agfa's similarly structured Agfacolor Neu was introduced in 1936. Unlike
Kodachrome, the color couplers in Agfacolor Neu were incorporated into the
emulsion layers during manufacture, which greatly simplified the processing.
Currently available color films still employ a multilayer emulsion and the same
principles, most closely resembling Agfa's product.
Instant color film, used in a special camera which yielded a unique
finished color print only a minute or two after the exposure, was introduced by Polaroid in 1963.
Color photography may form images as
positive transparencies, which can be used in a slide projector, or as color negatives intended for use in
creating positive color enlargements on specially coated paper. The latter is
now the most common form of film (non-digital) color photography owing to the
introduction of automated photo printing equipment.
 |
Technical Aspects 
Buisness Card
Technical Aspects
The camera is
the image-forming device, and photographic
film or a silicon electronic image sensor is
the sensing medium. The respective recording medium can be the film itself, or
a digital electronic or magnetic memory.[22]
Photographers control the camera and lens to
"expose" the light recording material (such as film) to the required
amount of light to form a "latent image"
(on film) or RAW file (in digital cameras) which, after appropriate
processing, is converted to a usable image.Digital cameras use an electronic image
sensor based on light-sensitive electronics such as charge-coupled device (CCD) orcomplementary
metal-oxide-semiconductor (CMOS) technology. The resulting
digital image is stored electronically, but can be reproduced on paper or film.
The camera (or 'camera obscura')
is a dark room or chamber from which, as far as possible, all light is excluded
except the light that forms the image. The subject being photographed, however,
must be illuminated. Cameras can range from small to very large, a whole room
that is kept dark while the object to be photographed is in another room where
it is properly illuminated. This was common for reproduction photography of
flat copy when large film negatives were used (see Process camera).
A general principle known from the birth of
photography is that the smaller the camera, the brighter the image. This meant
that as soon as photographic materials became sensitive enough (fast enough)
to take candid or what were called genre pictures, small detective cameras were
used, some of them disguised as a tie pin that was really a lens, as a piece of
luggage or even a pocket watch (the Ticka camera).
Buisness Card
