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backlighting
Describes lighting from a source behind the subject. It is usually used
in conjunction with other lights, but by itself it can separate the subject
from a dark background or create a halo effect around it.
Barn Doors
Attachment that fits on the front of a studio light and allows the photographer
to control the spread of light.
Bitmap/Bmp
An image format popular in the early days of PCs, but still used as the
native format by the Windows operating system.
blur filters
There are seven blur filters in Photoshop: Blur, Blur More, Lens
Blur, Gaussian Blur, Motion Blur, Radial Blur and Smart Blur. All work
by merging the colours of adjoining pixels together to give the visual
impression of unsharpness.
bracketing
Method of exposing one or more exposures on either side of the predicted
exposure to obtain the best result.
cable release
Cable which allows the shutter to be fired with minimum vibration or camera
shake; essential for long exposures.
calotype
A photographic process patented by William Henry Fox Talbot in England
and Wales on 8 February 1841, also known as Talbotype. The process was
a significant enhancement of Talbot's photogenic drawing process and used
silver iodide combined with gallic acid to enhance its sensitivity. After
exposure the paper was developed to produce a negative and then chemically
fixed to make it permanent. The calotype was the first negative/positive
process and it provided the basis of modern photography. See: Art
of Printmaking.
camera angle
Describes the position of the camera relative to the subject. Where the
camera is placed and the type of lens being used will determine how the
viewer perceives the subject.
camera lucida
An optical device used by artists that employs a prism to superimpose
a virtual scene or subject image onto a drawing board so that an outline
can be traced on to paper. It was invented by William Hyde Wollaston in
1807.
camera obscura
An optical device that came into use during the Renaissance. It consists
of a box or a darkened room with an opening on one side projecting an
image on to the facing side. It was used by Old
Masters as a drawing aid because it preserved
perspective. By the 18th century the use of lenses and a mirror set at
45 degrees made for smaller, portable camera obscurae.
candid photographs
Unposed images often taken without the knowledge of the subject. They
were made possible by small hand cameras; the first was reputedly taken
in 1892. The term was first used in 1930 by the Weekly Graphic.
carbon print
A number of carbon processes were described before Sir Joseph Swan patented
a process in 1864. Swan's was introduced the following year and found
commercial success by providing the photographer with ready-made materials.
His patents were bought out by the Autotype Company. The process produced
a print using carbon, which made it permanent and not susceptible to fading.
Carbon prints typically have a matt finish from black, grey to sepia and
other tones.
CCD
This is an image sensor; CCD stands for 'charge-coupled device'.
chromogenic print
A print made by the chromogenic development process and also known as
a dye-coupler print. The process was developed in the mid 1930s and is
the basis of the majority of modern colour silver-based photographic materials,
such as Kodachrome, Ektachrome, Kodacolor and Agfacolor
producing both negatives and direct positives. The prints are often incorrectly
referred to as C-[Type] prints, which refers, precisely, to a negative-positive
chromogenic paper called Kodak Color Print Material Type C available from
1955 to 1959.
chronophotography
A method of analysing movement by taking a series of still pictures at
regular intervals. It was pioneered separately by Etienne-Jules Marey
and Eadweard Muybridge among others from the early 1870s. In 1877 Muybridge
was able to confirm by chronophotography Marey's assertion that a horse
lifted all four hooves off the ground at once when trotting.
Clone brush
This is a tool used by graphics programs to retouch images.
close-up lens
A supplementary lens fitted to a camera lens that changes the focal length.
For close-up work, a positive lens effectively shortens the focal length
so that with a given lens-to-subject distance the near focusing limit
is reduced.
CMYK image mode
Cyan, Magenta, Yellow and Black (called K to prevent confusion with Blue)
is an image mode used for litho reproduction. All magazines are printed
with CMYK inks.
collodion process
A dry - or more commonly - a wet process using collodion as a medium to
support a light sensitive emulsion. The wet-collodion process was described
by Frederick Scott Archer in 1851 and, after refinement, was used by numerous
19th-century
photographers from c.1854 onwards. It remained dominant until
the mid 1870s. Collodion was also used to produce direct positives on
glass (ambrotypes) and tin (tintypes).
collotype
A screenless printing process invented by Alphonse Poitevin in 1856 and
commercially popular from the 1870s to 1920s.
colour depth
The number of colours in an image factor. This governs the quality of
your images.
colour temperature
A scale for measuring the quality of light in values of kelvin.
combination printing
A technique using two or more photographic negatives or prints to make
a single image. It was suggested by Hippolyte Bayard in 1852 for improving
the appearance of skies. It was first shown by William Lake Price in 1855.
0.G. Rejlander's Two Ways of Life of 1857 and Henry Peach Robinson's
Fading Away of 1858 are the best-known examples. The technique
was revived in the 1920s and 1930s often to produce surreal work. Digital
techniques have made it obsolete.
CompactFlash
A popular sort of memory card used in some digital cameras.
compound lens
A lens combining two or more individual elements, usually cemented together.
contact sheet
Method for printing negatives the same size as the film so that the photographer
can choose the images to be enlarged.
contemporary art
Embraces late 20th century contemporary
art movements in painting, sculpture and architecture, as well
as new media such as installation art,
(including sound), conceptualism and
video art.
copper plate
A printing plate used by any method of intaglio printing, etched or engraved
to take ink for transferring on to paper. Although the term copper plate
is widely used, plates are commonly made from copper or zinc.
cropping
Altering the boundaries of a photograph, negative or digital image to
improve the composition, remove unwanted elements, or to fit a method
of display.
cyan
Blue-green light; the complementary colour to red.
cyanotype
A process invented by Sir John Herschel and reported in 1842. The
prints are also known as blue-prints. The process is simple and produces
a characteristic blue image on paper or cloth. It was popular in the 1840s
and the 1880s. Its main use has been for the reproduction of architectural
or technical drawings.
daguerreotype
Announced on 7 January 1839 and presented to the world in August 1839
(except in England and Wales where it was patented), the daguerreotype
produced a unique image on a silver-coated copper plate. The process was
popular until the mid 1850s, although for longer in the United States,
until it was superseded by the more sensitive wet-collodion process. For
more details, see: History
of Photography (1800-1900).
darkroom
A space in which there is total darkness or limited illumination by red
or orange safelights so that light-sensitive materials such as film or
paper can be handled, processed or printed without being affected by unwanted
light.
depth of field
The distance in front of the point of focus and the distance beyond that
is acceptably sharp. Manipulation of this zone by extending or reducing
it can be an important aspect of creative control and view cameras have
evolved to facilitate this.
digital print
In photography this refers to a photograph produced from either a conventional
negative or a digital file by a digital printer. This includes various
fine art digital printing techniques, Inkjet and laser printing. See also:
Computer Art.
digital zoom
A way of magnifying an image using software techniques. Instead of pulling
your subject closer, a small patch of pixels is enlarged or interpolated
to make a detail look bigger than it really is.
dithering
A method of simulating complex colours or tones of grey using few colour
ingredients. Close together, dots of ink can give the illusion of a new
colour.
documentary
photography
A photographic depiction of the real world intended to show the subject
in a literal and objective way. Early examples include the work of Maxime
du Camp in recording the Near East, Roger Fenton in the Crimea; Mathew
Brady in the American Civil War, and the Parisian Eugene
Atget (1857-1927) in Paris. An important sub-genre is social documentary
photography, which records the human condition within a wider context.
Examples range from Thomas Annan in 1860s Glasgow, to Jacob Riis in 1890s
America and the Farm Security Administration photographers of the 1930s,
like Walker Evans (1903-75).
double-exposure
The recording of two superimposed images on the same piece of photo-sensitive
material. This may be through error or as part of the creative process.
dpi
Dots per inch - it is a measure of the quality of a printed image.
dry plate negative
Although produced from the late 1850s, they were more successfully introduced
from the early 1870s and quickly supplanted wet-collodion plates. Dry
plates matched and surpassed the sensitivity of wet-plates and were more
convenient to use.
Dusseldorf School
A group of students who studied at the Kunstakademie Dusseldorf in the
mid 1970s under the influential photographers Bernd
and Hilla Becher, producing clear, objective, black-and-white
images of industrial structures and architecture. Among the best-known
students at this innovative centre of postmodernist
art are Thomas Struth and Andreas
Gursky (b.1955).
DX code
Bar code on a 35 mm cassette that contains information such as film speed.
This is read inside the camera which adjusts itself automatically.
dye transfer print
This is a subtractive process for making colour prints from colour positives
or negatives. There were processes from 1875 but Eastman Kodak's wash-off
relief process of 1935, which was improved and reintroduced in 1946 as
the dye transfer process, was the most successful. Although complex it
produced attractive permanent prints with strong colours. See also: Colour
in Painting.
dynamic range
A measure of how a sensor records the bright and dark areas in a digital
photographic image.
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