Basic Photography Course

RADIANT ENERGY

Energy in the form of an

electromagnetic wave; for example, gamma rays,
X rays, ultraviolet energy, light, infrared energy,
radiant heat, and radio waves.

RADIATION

The process of emitting electromagnetic

energy.

RECIPROCITY LAW

Exposure is equal to the

intensity of the exposing light multiplied by the time
during which it acts. The same density should be
produced in a photosensitive material by an equal
exposure obtained by doubling the intensity of the
light and cutting the time of the exposure in half.
This law is only approximately followed by
photographic materials, and deviations from it are
known as "reciprocity law failures."

RECTILINEAR

In a straight line. When applied to a

lens, it indicates that images of straight lines
produced by the lens are not distorted.

REDUCING AGENT

A chemical constituent of a

photographic developer that changes the exposed
silver halide to metallic silver. Reducing agents
must be combined with other chemicals to confine
their activity to the silver grains that have been
exposed, to control the rate of reaction, and to
preserve the agent from combining with oxygen in
the air before it can do the work of development.
Reducing agents are also called photographic
developers.

AI-13

REFLECTED LIGHT

Light that has been deflected

from an opaque surface; not having been absorbed.

RELATIVE APERTURE

The relative aperture is the

ratio of equivalent focal length to the diameter of
the effective aperture. The symbol for relative
aperture written as a fraction is f/ followed by a
numerical value. To illustrate, the expression f/2
signifies that the diameter of the effective aperture
is one half of the focal length.

RELATIVE HUMIDITY

Ration of aqueous vapor

present in a space at a given temperature, as
compared with the greatest amount it could possibly
contain at that temperature.

REPLENISHER

An additional agent used to maintain

the chemical strength of a processing solution at a
constant level. (NMA)

RESOLUTION

In optics, the ability of a lens system

to reproduce an image in its finest details. See
RESOLVING POWER.

SHADOW

General term for the thinner areas of a

negative or the darker areas of an original.

SHOT

(1) Motion picture. The most basic unit of a

film; a single scene; the continuous action occurring
from the time the camera is turned on to the time it
is turned off. (2) Still picture. A single exposure or
photograph.

SHUTTER, BETWEEN-THE-LENS

A shutter

whose blades operate between two elements of the

RESOLVING POWER

The degree to which a lens,

optical system, or film emulsion is able to define the
details of an image, expressed as the maximum

number of black lines, with equal white interspaces

per millimeter discernible in the image. Results
obtainable for a given lens or emulsion vary with
contrast of the original image and with
development.

RESTRAINER

The ingredient of a photographic

developer that prevents too rapid development and
that minimizes chemical fog.

RETICULATION

A processing defect affecting

gelatin layers on a photographic film which, upon
drying, shows an irregular surface due to the
formation of small, irregular scaly patterns. Sharp
differences in the temperatures of successive
processing solutions and insufficient hardening of
the gelatin are the usual causes of reticulation.

RGB

The separate red, green, and blue color

(chrominance), or "C", video signals.

SCALE, FOCUSING

A calibrated scale that permits

focusing a camera without the use of a range finder
or ground glass.

SCRIM

Diffusing medium placed in front of lamps.

SEMIMATTE

A surface having a moderate,

interrupted sheen midway between glossy and dull,
or full matte.

SENSITIVITY

The degree to which an emulsion

reacts by the formation of a latent image under given
exposure conditions, especially as this relates to
exposure by different wavelengths (colors) of light.
(NMA)

SENSITIZING DYE

Any dyestuff used for

sensitizing a photographic emulsion.

SENSITOMETER

An instrument with which a

photographic emulsion is given a graduated series
of exposures to light of controlled spectral quality,
intensity, and duration.

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Basic Photography Course

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DOFMaster for Windows On-line Depth of Field Calculator DOFMaster for Mobile Devices On-line Depth of Field Table Hyperfocal Distance Chart Articles FAQ Recommended Books Support Contact Links Home As an Amazon Associate I earn from qualifying purchases.	contents <- previous page next page -> RADIANT ENERGY Energy in the form of an electromagnetic wave; for example, gamma rays, X rays, ultraviolet energy, light, infrared energy, radiant heat, and radio waves. RADIATION The process of emitting electromagnetic energy. RECIPROCITY LAW Exposure is equal to the intensity of the exposing light multiplied by the time during which it acts. The same density should be produced in a photosensitive material by an equal exposure obtained by doubling the intensity of the light and cutting the time of the exposure in half. This law is only approximately followed by photographic materials, and deviations from it are known as "reciprocity law failures." RECTILINEAR In a straight line. When applied to a lens, it indicates that images of straight lines produced by the lens are not distorted. REDUCING AGENT A chemical constituent of a photographic developer that changes the exposed silver halide to metallic silver. Reducing agents must be combined with other chemicals to confine their activity to the silver grains that have been exposed, to control the rate of reaction, and to preserve the agent from combining with oxygen in the air before it can do the work of development. Reducing agents are also called photographic developers. AI-13 REFLECTED LIGHT Light that has been deflected from an opaque surface; not having been absorbed. RELATIVE APERTURE The relative aperture is the ratio of equivalent focal length to the diameter of the effective aperture. The symbol for relative aperture written as a fraction is f/ followed by a numerical value. To illustrate, the expression f/2 signifies that the diameter of the effective aperture is one half of the focal length. RELATIVE HUMIDITY Ration of aqueous vapor present in a space at a given temperature, as compared with the greatest amount it could possibly contain at that temperature. REPLENISHER An additional agent used to maintain the chemical strength of a processing solution at a constant level. (NMA) RESOLUTION In optics, the ability of a lens system to reproduce an image in its finest details. See RESOLVING POWER. SHADOW General term for the thinner areas of a negative or the darker areas of an original. SHOT (1) Motion picture. The most basic unit of a film; a single scene; the continuous action occurring from the time the camera is turned on to the time it is turned off. (2) Still picture. A single exposure or photograph. SHUTTER, BETWEEN-THE-LENS A shutter whose blades operate between two elements of the RESOLVING POWER The degree to which a lens, optical system, or film emulsion is able to define the details of an image, expressed as the maximum number of black lines, with equal white interspaces per millimeter discernible in the image. Results obtainable for a given lens or emulsion vary with contrast of the original image and with development. RESTRAINER The ingredient of a photographic developer that prevents too rapid development and that minimizes chemical fog. RETICULATION A processing defect affecting gelatin layers on a photographic film which, upon drying, shows an irregular surface due to the formation of small, irregular scaly patterns. Sharp differences in the temperatures of successive processing solutions and insufficient hardening of the gelatin are the usual causes of reticulation. RGB The separate red, green, and blue color (chrominance), or "C", video signals. SCALE, FOCUSING A calibrated scale that permits focusing a camera without the use of a range finder or ground glass. SCRIM Diffusing medium placed in front of lamps. SEMIMATTE A surface having a moderate, interrupted sheen midway between glossy and dull, or full matte. SENSITIVITY The degree to which an emulsion reacts by the formation of a latent image under given exposure conditions, especially as this relates to exposure by different wavelengths (colors) of light. (NMA) SENSITIZING DYE Any dyestuff used for sensitizing a photographic emulsion. SENSITOMETER An instrument with which a photographic emulsion is given a graduated series of exposures to light of controlled spectral quality, intensity, and duration. contents Basic Photography Course <- previous page next page ->	As an Amazon Associate I earn from qualifying purchases.
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