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Glossary
A
Additive
color: A way to produce
colors of light by mixing light of the three additive primary colors
- red, green, and blue. Varying proportions of the additive primaries
can be combined to create light of all other colors, including white,
which is a mixture of all wavelengths.
Albumen:
Egg white; used in early photographic emulsions as a coating for
papers. Also used for glass plates.
Alkali:
a substance with a pH above 7. Developers are usually alkaline
solutions.
Ambient
light: see available
light
Ambrotype:
a collodion wet-plate process in which the emulsion was coated on
a glass plate. The negative image produced was visible as a positive
image when the glass was backed with a dark material.
Aperture:
the size of the lens opening through which light passes. The relative
aperture is measured as the focal length of the lens divided by
the diameter of the aperture; this is expresses as an f-number:
f/8, f/11, etc.
Aperture-priority:
a mode of automatic exposure in which the photographer selects the
aperture and the camera sets the shutter speed that will produce
the correct exposure.
Archival
processing: processing
of film and paper designed to protect the print or negative as much
as possible from premature deterioration caused by chemical reactions.
Artificial
light: light from an electric
lamp, a flash bulb, or electronic flash. Often describes lights
the photographer has set up to illuminate a scene
Automatic
focus: a system by which
the camera adjusts its lens to focus on a given area. Abbreviated
AF
Av:
abbreviation for aperture value. Used on some camera information
displays as a shortened way to refer to aperture settings (f-stops)
Available
light: the light that already
exists where a photograph is to be made, as opposed to light brought
in by the photographer. Often implies a relative dim light. Also
called ambient light or existing light
Glossary
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