PHOTOGRAPHY GLOSSARY (P-R)
Photo
Glossary - P
•Painting with light - technique of lighting large,
dark interior. The camera, mounted on a tripod, is given a long
time
exposure. The photographers moves continuously around the
interior, giving flash or battery powered photoflood illumination
to the shadow areas.
•Pan and tilt head - tripod head allowing the camera
to be tilted up and down or turned through a 360° arc.
•Panchromatic - photographic
emulsion sensitive to all the colors of the visible spectrum and
to a certain amount of ultra-violet light. The sensitivity is
not uniform throughout the spectrum.
•Panchromatic vision filter - filter through which
the subject can be viewed approximately as it would appear in
monochrome as recorded by a panchromatic
emulsion.
•Panning - technique of photographing moving subjects.
While the shutter is open, the camera is swung in the same direction
as the subject is moving. This creates a blurred background, but
a sharp subject.
•Panorama - picture presenting a continuous view
of the landscape, produced either by using a panoramic camera
or from a composite of several images.
•Panoramic camera - camera with a special type of
scanning lens which rotates on its rear nodal
point and produces an image of the scanned area on a curved
plate or film.
•Paper base - support for the emulsion used in printing
papers.
•Paper characteristic curve - describes a
graphical relationship between exposure values and image density
of a printing paper. Each brand of paper may have a different
initial characteristic curve. The shape of the curve can be altered
by different developers, development times, temperatures, and
toning.
•Paper grade - numerical and terminological description
of paper contrast: numbers 0 - 1 soft; number 2 normal; number
3 hard; number 4 - 5 very hard; number 6 ultra hard. Similar grade
number from different manufacturers do not have the same characteristics.
•Paper safe - light-tight container for unexposed
photographic papers, with an easy open positive closing lid.
•Parabolic mirror - silvered glass or metal reflector
with a parabolic axial cross-section, used to produce near parallel
rays from a light source positioned at its geometrical focus.
•Parallax - difference between the image seen by
a viewing system and that recorded on film. Only TTL
viewing systems avoid parallax error.
•Paraphenylenediamine - reducing agent used in some
fine grain and color developers.
•Paraphotography - general term for non-silver-halide
image forming processes.
•Paraxial - rays nearest the optical axis of a lens.
•Patch chart - squared pattern test strip often made
when color printing by the additive method.
•PCT - see Photo
color transfer.
•PEC - see Photo-electric
cell.
•Pellicle (pellicule) - thin film used in one-shot
color cameras as a semi-reflecting surface.
•Pentaprism - optical device, usually fitted on 35mm
cameras, which makes it possible to view the image while focusing.
A mirror device laterally reverses the image so that the scene
is viewed through the camera upright and the right way round.
•Percentage solution - solution containing a given
quantity of a dissolved substance in a stated volume of solvent.
•Perforations - accurately spaced holes punched throughout
the length of film for still cameras. Basically the perforation
function as a guide for precision registration of film and also
provide mechanical movement from frame to frame.
•Periphery photography - technique used to photograph
the entire inner or outer surface of a cylinder or tube.
•Permanence tests - methods of establishing whether
long term permanence of an image has been achieved.
•Perspective - relationship of size and shape of
three-dimensional objects represented in two-dimensional space.
•Petzval lens - early lens system developed by Joseph
Petzval. It had a very wide aperture and was relatively free from
aberration. Many modern lenses have developed from this simple
three-element design.
•Phenidone - reducing agent used
in many fine grain solutions.
•Phenol varnish - resin used to produce a hard durable
top coating.
•Phosphorescence - property held by some materials
of absorbing light of one wavelength
and emitting it as light of a different wavelength.
•Phosphotophotography - technique of projecting an
infrared image on a phosphorescent surface.
•Photo color transfer - method
of making color enlargements by exposing on full size sheet film
which is then soaked in a activator solution and rolled in face
contact with receiving paper. The sandwich is then left in normal
light for 6-8 minutes and peeled apart to give a finished print.
•Photo elasticity - method of determining stress
patterns in structures with the aid of polarized
light.
•Photo-electric cell - light
sensitive cell. Two types are used in exposure meters. A selenium
cell generates electricity in proportion to the amount of light
falling upon its surface. A cadmium sulfide cell offers a resistance
to a small electric charge when light falls upon it. Cadmium sulfide
cells are more sensitive then selenium, especially at low light
levels.
•Photo-engraving - production of a relief printing
surface by chemical or mechanical means, with the aid of photography.
•Photo-etching - technique of contact printing an
image on lith
film on a presensitized zinc plate which is then processed
and chemically etched to give a relief image.
•Photo file index print - makes ordering reprints
and enlargements easy. A small print shows a positive, "thumbnail"
version of every picture on an APS roll. Each thumbnail picture
is numbered on the index print to match the frames inside the
cassette.
•Photoflood - artificial light source using a tungsten
filament lamp and a dish reflector.
•Photogenic drawing - original name given by William
Fox Talbot to his earliest method of recording camera images.
•Photogram - pattern or design produced by placing
opaque or transparent objects on top of a sensitive emulsion,
exposing it to light and then developing it.
•Photogrammetry - method of making precise measurements
from photographs.
•Photography - literally writing or drawing with
light (from the Greek words photos meaning light and graphos,
writing). First suggested by Sir John Herschel to William Fox
Talbot in 1839.
•Photogravure - method of printing photographs from
an etched copper plate.
•Photolamp - tungsten filament photographic lamp
with a large diffused bulb, giving light of 3200 K (kelvin).
•Photolinen - laminate of linen and paper coated
with black and white photographic emulsion. It is used for photographic
wall coverings.
•Photolithography - lithographic printing process
using an image formed by photographic means.
•Photometer - instrument for measuring light being
reflected from a surface. It works by comparing the reflected
light with a standard source produced within the photometer.
•Photomicrography - system
of producing larger than life photographs by attaching a camera
to a microscope.
•Photon - particle of light energy. It is the smallest
quantity of radiant energy that can be transmitted between two
systems.
•Photo-reportage - use of photographs in newspapers
and magazines, to supplement or replace written journalistic accounts.
•Photo-resistor - photoelectric cell which varies
in its electrical resistance according to the light received.
•Photo-silkscreening - method of silkscreening images,
using a stencil produced photographically.
•Photo telegraphy - transmission of pictures between
two points by means of radio or telegraph. A print is wrapped
around a cylinder and scanned by a small spot of light. Reflected
light values are transmitted as a stream of signals. They control
an exposing light source at the receiving station, which exposes
light sensitive material on a similar drum.
•Photo-transistor - light sensitive electronic component
which functions as a switch. Used for slave firing of electronic
flash heads.
•pH scale - numerical system running
from 0-14 and used to express the alkalinity or acidity of a chemical
solution. 7 is neutral. Solutions with a lower pH value are increasingly
acidic, and those with a higher pH value are increasingly alkaline
•Physical development - system of development in
which silver is contained in suspension within the developer and
is attracted to the emulsion by silver halides which have received
exposure.
•Physiogram - photographic patter produced by moving
a regulated point of light over a sensitive emulsion.
•Pictorialist - photographs which are a picturesque,
decorative art in their own right and appeal to the viewers sense
of beauty.
•Piezo-electric flash - tiny flash bulbs (normally
housed in flash cubes) which can be fired by a very low current
produced by striking a piezo-electric crystal. Such bulbs can
therefore be used without a battery.
•Pigment - coloring material that is insoluble in
the liquid carrier with which it is mixed. Examples include paint
or poster color.
•Pigment processes - making a positive print by using
the property of bichromated colloids by changing their physical
characteristics with exposed light. Gum
bichromate is a pigmented process.
•Pinacryptol - yellow and green dye powders which
are used in desensitizing solutions.
•Pincushion distortion - lens
aberration
causing parallel, straight lines at the edge of the image to curve
toward the lens axis.
•Pinhole camera - camera without a lens which uses
a very small hole pierced in one end to allow light to pass through
and form an image on the back of the camera which can be covered
by film.
•Pixels - abbreviation for picture elements. The
tiny squares of light making up the picture are transmitted in
digital form and reconstituted as a visual image.
•Plane - imaginary straight line on which image points
may lie or which passes at right angles through a set of points
perpendicular to the optical
axis.
•Plates - early photographic glass plates coated
with emulsion.
•Plate camera - camera designed to take glass plates
but often adapted to take cut
film.
•Platinotype - obsolete contact printing process
popular among pictorialists.
•Point source lamp - arc type lamp producing light
from a small gap between two carbon rods.
•Polarization - light said to travel in a a wave
motion along a straight path, vibrating in all directions. Polarization
can be brought about with a polarizing filter which causes light
to vibrate in a single plane only. Polarizing filters are used
over camera lenses and light sources to reduce or remove specular
reflection from the surface of objects.
•Polarized light - rays of light
that have been restricted to vibrate in one plane only.
•Polarizing filter - colorless
gray filter made from stressed glass. Polarizing filters are used
over light sources or camera lenses to reduce or remove specular
reflection from certain types of surfaces.
•Polaroid camera - an instant picture camera designed
for Polaroid materials.
•Pola-screen - another term for a polarizing
filter.
•Portrait lens - lenses produced specifically for
portraiture. They usually have a long focal length and produce
a slightly diffused image.
•Positive - in photography, the production of prints
or transparencies in which light and dark correspond to the tonal
range of the original subject.
•Positive lens - simple lens that causes light rays
from a subject to converge to a point.
•Positive/positive printing - process for printing
a color transparency directly on paper to produce a positive print.
•Posterization - photographic
technique using a number of tone separated negatives which are
printed on high contrast material. A master negative is made by
printing these in register. The final print from this contains
selected areas of flat tone in place of continuous tone. Sometimes
incorrectly referred to as solarization.
•Potassium bichromate - chemical
used in chrome intensifiers.
•Potassium bromide - chemical used as a restrainer
in most developing solutions and as a rehalogenizing
agent in bleaches.
•Potassium carbonate - highly soluble alkaline accelerator
used in most general purpose and print developing solutions.
•Potassium chloride - chemical used in some bleaches
and sensitizers.
•Potassium citrate - chemical used in blue and green
toners.
•Potassium dichromate - See Potassium
bichromate.
•Potassium ferricyanide - chemical used in Farmer's
reducer as a bleach.
•Potassium hydroxide - caustic potash. Highly active
alkali, used as the basis for high contrast developing solutions.
•Potassium iodide - chemical used in bleaches, toners
and intensifiers.
•Potassium metabisulfite - acidifier used in fixers
and stop baths.
•Potassium permanganate - chemical used extensively
in reducers, bleaches and toners.
•Potassium persulfate - chemical sometimes used in
super-proportional reducers.
•Potassium sulfide - chemical used in sulfide
toning.
•Potassium thiocyanate - chemical used in some fine
grain developers as a silver solvent.
•Prehardener - chemical solution used to harden the
gelatin of an emulsion prior to processing.
•Preservative - chemical, commonly sodium
sulfite, used in developing solutions to prevent rapid oxidation
of the reducing agents
in use.
•Preset focus shooting - technique in which focus
is set at a predetermined setting and the shutter is released
when the subject moves into the focus point.
•Pre-soak - preparatory water bath for film or paper
prior to processing that prevents uneven development. It is essential
in some color processes.
•Press focus lever - lever found on the between-lens
shutter of many large format cameras. It allows the shutter blades
to be held open for lens focusing no matter what shutter speed
has been set.
•Primary colors - three primary additive colors of
the spectrum in terms of transmitted light. These colors are blue,
green and red.
•Principal axis - imaginary line which passes through
the center of curvature of all the lens elements.
•Principal planes - imaginary lines which pass through
the nodal
planes of a lens system.
•Principal point - point from which the focal length
is measured. The principal point of a simple lens is located at
the center of the lens. Compound lenses have two principal points,
the location of which cannot be determined by appearance.
•Print - in photography is an image, normally positive,
which has been produced by the action of light on paper or similar
material coated with a light sensitive emulsion.
•Printing - process employed to make one or a number
of images on paper or similar material.
•Printing-in - system of local
shading control used in printing in which additional exposure
is given to selected areas of a print.
•Printing-out papers - light sensitive printing papers
which visibly darken during exposure to sunlight. Also referred
to as contact printing papers.
•Prism - transparent medium capable of bending light
to varying degrees, depending on wavelength.
•Processing - sequence of steps whereby a latent
photographic image is converted into a visible, permanent image.
•Process lens - lens system designed specifically
for high quality copying.
•Projection cutting - any method of printing in which
the image is optically projected on the sensitized material.
•Projector - apparatus used to display enlarged still
or moving images on to a screen.
•Proportional reducer - chemical method of reducing
excess density and contrast from a photographic negative.
•Protective toning - toning process used to protect
black and white prints from fading and give archival permanence.
Usually used selenium or gold toners.
•Pulling - method of underrating the normal ISO speed
of a film to produce an overexposed latent image.
•Pushing - method of overrating
the normal ISO speed of a film to produce an underexposed latent
image. Used to increase the working speed of a film.
•Push processing - increasing the development time
of a film to increase its effective speed. See Pushing.
•Pyro - reducing agent sometimes used in developing
solutions.
Photo
Glossary - Q
•Quantum - smallest indivisible unit of radiant energy.
•Quarterplate - negative or print format measuring
3 ¼ x 4 ¼ inches. It's one quarter the size of a full plate (8
½ x 6 ½ inches).
•Quartz-iodine lamp - compact tungsten filament lamp
designed to maintain its color temperature and light intensity
throughout its working life.
Photo
Glossary - R
•Rack and pinion focusing - mechanical focusing system
used on copying or monorail cameras. A pinion engages a rack on
a slide. Focusing is achieved by turning a knob or wheel, which
moves the lens or image panel.
•Radiography - technique of using
X-rays, gamma rays and charged particles to form shadow images
on photographic materials. Used in medical and industrial research
because of its ability to penetrate opaque
objects.
•Rangefinder - focusing system
which measures the distance from camera to subject.
•Rapid fixer - fixing solution that uses ammonium
thiocyanate or thiosulfate instead of hypo.
•Rapid rectilinear - lens system
composed of two matching doublet lenses, symmetrically placed
around the focal aperture. It was introduced by Dallmeyer and
Sternheil and removed many of the aberrations present in more
simple constructions.
•Rayographs - term coined by Man Ray and his friends
for pictures made by placing directly on photographic paper (i.e.
photograms).
•Rear curtain sync - when the flash fires an instant
before the second or rear curtain of the focal plane shutter begins
to move. When slow shutter speeds are used, this feature can create
a blur effect from the ambient light, i.e., patterns following
a moving subject with subject movement frozen at the end.
•Rear focus - refers to the focused area behind
the picture's subject.
•Rear focusing system - system where only the rear
lens group moves during focusing. It eliminates changes in the
physical length of the lens during focusing.
•Rebate - margin on photographic film surrounding
the image area.
•Reciprocity failure - in photographic
emulsions occurs when exposure times fall outside a films normal
range. At these times an increase in exposure is required in addition
to the assessed amount. This can be achieved either by increasing
intensity or time.
•Reciprocity law - states that
exposure = intensity x time, where intensity is equal to the amount
of light and time is equal to the time that amount of light is
allowed to act upon the photographic emulsion.
•Reconstituted image - photograph produced by translating
light from the subject into electronic signals.
•Recycling time - time it takes a flash unit to recharge
between firings.
•Red eye - effect encountered when light from a flash
unit travels parallel to the lens axis during exposure.
•Reducers - solutions which
remove silver from negatives and prints. They are used to diminish
density and alter contrast on a photographic emulsion.
•Reducing agent - chemical in
a developing solution which converts exposed silver halides to
black metallic silver.
•Reflected light - light bounced off a subject, not
falling on it.
•Reflected light reading - measurement by a light
meter of the amount of reflected light being bounced of the subject.
The light meter is pointed towards the subject.
•Reflecting telescope - telescope using a concave
parabolic mirror to increase focal length and focus light at a
point.
•Reflections - rays of light
which strike a surface and bounce back again. Specular reflection
occurs on even, polished surfaces; diffuse reflection occurs on
uneven surfaces, when light scatters.
•Reflector - any substance from which light can be
reflected. It also describes a white or gray card used to reflect
from a main light source into shadow areas.
•Reflex camera - camera system which uses a mirror
to reflect incoming image rays on to a ground glass screen, providing
a system of viewing and focusing. See also SLR.
•Reflex lens - alternative term for mirror
lens.
•Refraction - change in direction of light rays as
they pass obliquely from one transparent medium to another of
different density, e.g. air to glass.
•Refractive index - numerical value indicating the
light bending power of a medium such as glass. The greater the
bending power, the greater the refractive index.
•Register - exact alignment when
overlaying separate images.
•Register punch - punched used to make alignment
holes in film or paper for registering
images.
•Rehalogenization - process
by which black metallic silver is converted back to silver halides.
It is used in bleaching for toners
and intensification.
•Relative aperture - measurable diameter of the diaphragm
divided by the focal length of the lens in use and expressed in
terms of "f"
numbers, marked on the lens barrel.
•Replenishment - addition of chemicals to a processing
solution to maintain its characteristics, e.g. developers are
replenished with reducing agents as the old ones are exhausted
through use.
•Resin coated paper (RC) - printing paper with a
water repellent base. RC Paper can be processed faster, require
less washing, and dry more quickly than fiber based papers.
•Resist - protective but removable layer applied
to a surface in the form of a pattern or image. Used to prevent
chemicals solutions reaching covered areas.
•Resolving power - ability of the eye, lens or photographic
emulsion to determine fine detail. In photography, the quality
of the final image is a result of the resolving power of both
the lens and the sensitive emulsion. Resolution is expressed in
terms of lines per millimeter which are distinctly recorded or
visually separable in the final image.
•Restrainer - chemical constituent of developing
solutions which helps prevent reducing agents from affecting unexposed
halides and converting them to black metallic silver.
•Reticulation - regular crazed pattern created on
the emulsion surface of negatives which is caused by extreme changes
of temperature or acidity/alkalinity during processing.
•Retrofocus - type of lens design with a negative
lens element positioned in front of the diaphragm and a positive
lens element positioned at the rear of the diaphragm. This makes
the distance from the rear of the lens to the focal plane longer
than the lens focal length. Retrofocus design has been adopted
in wide angle lenses so the rear of the lens does not impede the
movement of an SLR camera's reflex mirror.
•Retouching - after treatment carried out on a negative
or print, in the form of local chemical reduction, local dye or
pencil additions or air-brushing. The purpose is to remove blemishes
on the negative or print.
•Reversal materials - materials specifically designed
to be processed to a positive after one camera exposure.
•Ring flash - ring shaped electronic flash unit attached
to the front of a lens. Used to give even frontal lighting in
closeup situations.
•Rinse - brief clean water wash between steps of
a processing cycle to reduce carry-over of one solution into another.
•Rising front - camera movement enabling the front
lens panel to be raised or lowered from its central position on
most view cameras.
•Rods - receptors forming part of the retina at the
back of the eye sensitive only to variations in brightness, not
color.
•Roll film - refers to 120, 220 and 620 film formats.
•Roll film adaptor - specially designed attachment
for cameras designed for cut
film, enabling roll film to be used.
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