Glossary
Time-lapse photography
Recording objects at timed intervals (seconds, hours, days) to show how they change. The camera remains in a fixed position while
single-frame exposures are made at regular intervals to document the moving object, such as clouds moving across the sky or a flower blooming.
Toning
Changing the overall color of a photograph. Toning can be done in the course of or following the development procedure. During the
development process, a number of factors can all effect the final tone, such as the original chemical composition of the print or developer,
temperature, strength of the developer, length of development, and means of drying the print. After development, toning changes the chemical composition
by depositing other materials on the print, including those containing sulfur or stable materials such as copper, gold, iron, mercury,
palladium, platinum, selenium, and vanadium. Gold toning, which usually increases contrast, image stability, and permanence, originated during the era
of the Daguerreotype. It was commonly used with
albumen prints in order to impart a rich purplish-brown color. Selenium is the most
commonly used toner in the twentieth century. It slightly increases the tonal range and density of a print, giving it a darker, richer tone. Like gold,
selenium coats the silver in the emulsion, producing a more stable print. Selenium toning can also produce a "split-tone" photograph on certain
papers, creating an image with silvery highlights and rich burgundy shadows. Finally, many photographs use toners to create coloristic effects
ranging from various browns, greens, and blues as well as purple, red, and yellow.
Transillumination
The method of viewing transparent or translucent images such as slides, transparencies, or autochromes. The positive image is visible when
lit from behind or projected onto a surface.
Transparency
A positive photographic image on a transparent or translucent support, such as glass or film. Transparencies are intended to be viewed by
a transmitted light source, such as a projector or a light box.
Variant
One of two or more photographs of the same subject with only slight differences. A variant can be produced in several ways. A photographer
can take multiple photographs of the same subject under constant conditions, without significantly changing lighting or exposure time (for
example, landscape in a vertical format and then in a horizontal format). Variants can be produced in the darkroom by altering the tonality of the print.
A variant can be a cropped (trimmed) version of the same image.
Varnishing
As a final step, negatives and prints are often coated with a shellac- or resin-based liquid that provides a smooth appearance and an extra layer
to protect against scratches or other injury. Varnishes dry relatively quickly, producing a hard finish. To help reduce processing time, before
exposure photographic papers can be coated on both sides with a plastic material similar to varnish. "Supercoats" were introduced around the
late 1960s.
View camera
A large camera, so-called for the ground-glass viewing screen located on the same plane as the film. This screen, which receives light
directly from the picture-taking lens, reveals precisely what the film will record. The typical view camera has four basic structural parts: a bed, the
support on which the other parts rest and move, historically a dual track framework although most modern view cameras are monorail; the
front, which has various mechanisms that support and allow adjustments to the lens; the back, which has the same freedom of movement as the
front but incorporates a ground-glass viewing screen that moves out as a unit to accept a film holder and hold it in place; and the bellows, made
of pleated leather or rubber-coated canvas, which provides a light-tight connection between front and back. Instead of bellows, some early
view cameras were simply two boxes that could slide into one another.
Vignette
A photograph in which a central image dissolves into the area around it, creating a soft frame around the picture. Vignettes usually fade into
a field of white. The effect can be achieved by photographing the subject through an oval opening in a piece of opaque paper or board placed
on the camera lens or by printing the negative through a frame with a partially translucent inner edge. During the nineteenth century, oval
vignetting was popular in portraiture.
Waxed paper negative
A variant of the calotype negative. Before being sensitized in a silver nitrate bath, a paper negative was waxed to improve its translucency
for printing. This method, published by Gustave Le Gray (1820-1882) in 1851, was more time consuming than the calotype process but could
hold finer detail. The long exposure time required for the waxed paper negative was useful for still lifes and landscapes as well as travel
photography because it could be prepared and sensitized many days before exposure.
Wet collodion negative
The first fully practical negative on glass. Printing from glass negatives allowed high resolution of fine detail and a short exposure time,
ranging from several seconds to one or two minutes. The glass plate negative was prepared by covering it with collodion, a sticky emulsion of
guncotton dissolved in ether and alcohol with potassium iodide that had been sensitized with a solution of silver nitrate. While still tacky, but not dry,
the negative was inserted in the camera, exposed, and immediately returned to the darkroom for developing with pyrogallic and acetic acids
or ferrous sulfate. Fixed, washed, dried, and varnished, the glass negative was then ready for printing. The inherent nature of the wet collodion
glass negative required immediate access to a darkroom, and those photographing out-of-doors, often in exotic locales, traveled with created dark
tents s where it has not occurred.
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