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Aberration: A
lens defect, resulting in image distortion.
AE: Automatic Exposure,
Autoexposure. Mode in which the camera adjusts shutter speed and aperture to
achieve correct exposure.
AF: Automatic Focus,
Autofocus. System by which the camera and lens adjust to focus on a specific
part of the image.
Accelerator: Alkali
used to increase activity of developing agents.
Acid Free: Specially
prepared mounting boards, album pages, tissues, and storage boxes designed to
house prints for maximum archival permanence.
Alternative Processes:
Processes other than modern, conventional silver-halide photography or digital
photography (e.g. bromoil, carbro, cyanotype, platinum, etc.). Even then, some
silver-halide processes are regarded as "alternative," such as Printing Out
Paper (POP) and Argyrotype.
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Ambient Light: The
general light level, before you start adding photographic lights or on-camera
flash.
Ambient Temperature:
Crudely, room temperature. Some photographic chemicals can be used "at ambient"
(with appropriate correction of processing times) while other types need to
be heated or cooled to a specific temperature required by a particular process.
Angle of View: Measures
the area a lens can cover (e.g., wider coverage = larger angle).
Aperture: Literally,
"opening." A lens with a big opening is said to have a large aperture; one with
a small opening is said to have a small aperture. The standard sequence of apertures
is such that each smaller aperture allows 1/2 of the light through as compared
with the next. The sequence used today is f/1, f/1.4, f/2, f/2.8, f/4, f/5.6,
f/8, f/11, f/16, f/22, f/32, f/45, f/64, f/90, f/128. Each is approximately
1.4x the one before; the actual ratio is the square root of two, because aperture
is a linear measurement while light passing power increases as the square of
that measurement.
Aperture Priority:
Mode of automatic exposure in which the camera adjusts shutter speed according
to a manually selected aperture.
Apochromatic: Literally
"away from color." All lenses focus different colors at different focal planes.
Most lenses are "achromats" (from "no color") and bring blue and red to a common
focus. A cubic apochromat brings three wavelengths to a common focus, and a
quartic apochromat brings four to a common focus. Some manufacturers use "apo"
or "apochromat" more as an advertising tool than in any very scientific sense.
Archival Permanence:
The life of a well made, well stored print is several centuries, though the
life of a poorly processed and badly stored print may be months, weeks, or even
days. The maximum life of a film negative under anything like normal storage
is unlikely to exceed 100 years. There is no such thing as "permanence," and
there is no absolute definition of "archivally permanent," though there are
ANSI and other standards defining maximum levels of residual hypo and other
parameters which affect keeping qualities.
ASA: An old film
sensitivity rating, replaced by ISO.
Aspect Ratio: The
height-to-width relationship of a film or image format (e.g. a 6x12cm negative
is said to have a 2:1 aspect ratio), a term that assumes importance in any comparative
discussion of panoramic camera formats.
Aspheric: Most lens
surfaces are "common" or "spherical" curves. Grinding (or increasingly often,
molding) aspheric ("varying slightly from sphericity"; in effect varying curvatures
on a single lens surface) surfaces allows better correction with the same number
of lens elements, or the same degree of correction with fewer elements.
Astigmatism: the
inability of a lens to bring tangential and radial lines to a common focus.
Available Light:
What it says: the light that is available, a little or a lot, artificial or
natural, without the addition of flash or other photographic lighting.
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B2B:
Business to business.
B2C: Business to
consumer.
Back Lighting: Light
from behind the subject, heading toward the camera Barn Doors: Movable flags
attached to a light, used to control the spread of the beam.
Barrel Distortion:
Lens aberration that causes straight lines to bow out, away from the center.
Baryta: Barium sulfate
used as brightener in Fiber-Base (FB) papers. Some European papers are actually
labeled "Baryt." Bellows: An expandable, flexible, light-tight, accordion-folded
instrument used in view cameras to connect the lens to the film plane, as well
as in other formats for close-up photography.
Bracket: To make
multiple exposures, some overexposed and some underexposed according to the
indicated meter reading, used to control brightness, contrast, color and to
ensure accurate exposure.
Brightness: A subjective
impression of the lightness of an object. Bulb: Shutter speed setting, marked
B, that holds open the shutter as long as the release button is held down.
Burn: To darken a
specific image area during printing by giving it additional exposure.
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C-41:
Standard process for developing color negatives.
Camera: A picture-taking
device, usually consisting of a light-tight box with a film, shutter and lens.
Chromatic Aberration:
Lens aberration that focuses different colors of light at different angles.
Chrome: Slang term
for slides or transparencies.
Chromatic Aberration:
The inability of a lens to bring all colors to a common focus. On the optical
axis, this results in points of light being represented with a halo around them;
farther out (transverse or lateral chromatic aberration) it results in color
fringing. The two types of chromatic aberration can exist independently.
Chromogenic Film:
Monochrome (black and white) film in which the image is composed of dyes rather
than of silver. The technology is similar to that of color films, hence the
name. It is processed in color negative chemistry (e.g. C-41), allowing it to
be processed along with color negative films.
Circle of Confusion:
Any sufficiently small circle is indistinguishable to the human eye from a point.
As long as a lens resolves a point as a circle that is small enough, its resolution
is adequate: though a lot depends on how much the image is to be enlarged, and
the lighting conditions under which it is to be displayed, to say nothing of
variations in individual eyesight. The size of the circle of confusion is a
matter of dispute, especially with classic large format lenses.
CMYK: Acronym for
Cyan, Magenta, Yellow, Black, the primary subtractive colors and black. CMYK
commonly refers to a type of the ink colors used in color offset printing.
Continuous Tone:
An image possessing a smooth gradation of tones through the gray scale, from
pure black to pure white.
Cool: Description
of bluish colors, or light, or color balance, that is associated with cold temperatures.
Color Balance: A
film's or paper's response to specific colors of light. Films are adjusted for
optimum color reproduction in specific color temperatures of light (i.e., tungsten
or daylight-balanced) Color Correction Filters: Camera filters made in additive
(red, green, blue) and subtractive (cyan, magenta, yellow) primary colors, in
a wide range of strengths, for making fine adjustments to image color.
Color Temperature:
A measure of the color of a light source, usually expressed in degrees Kelvin
(°K). Low color temperatures look red or yellow, which is "warm" to the eye
(and to film); high color temperatures look blue or "cold."
Coma: A lens aberration
which results in a point of light becoming progressively elongated toward the
edge of the field, fanning out into comet-like shapes in a worst-case scenario.
Continuous Light Sources:
What the name says: lights that stay on continuously, as distinct from flash.
Contrast: (1) Subject
brightness range: a contrasty subject has extremes of light and dark, a flat
subject is in a more limited range of grays; (2) Image brightness range: a contrasty
image is usually lacking in mid tones and is made up of dark shadows and bright
highlights, while a flat image is dull and lacks sparkle; (3) Lens contrast:
a contrasty lens does not degrade shadows and veil the image, but a flat lens
does.
Coverage, Lens: The
area of the image cast by a lens (also referred to as "image circle"). A lens
which can cast a sharp image only over a small area is said to have a small
coverage. Lenses of the same focal length may vary widely in coverage, according
to their angle of view: a 50mm lens for a 35mm camera may cover only the 35mm
frame, while a 47mm f/5.6 Schneider Super Angulon XL can cover a 4x5" sheet
of film.
Crop: Adjusting the
edges of an image, typically to improve composition.
Curvature of Field:
A lens aberration in which the image is formed on a curved plane, instead of
a flat surface.
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Daylight:
The color temperature range of daylight varies quite widely, but it may be taken
as around 5500K. Electronic flash typically ranges from 5500-6000K.
Daylight-Balanced Film:
Film designed to be exposed to light with a color temperature of around 5500K.
Dedicated Flash:
A flash unit which is designed to work only with one line or model of camera.
Some flash units are made with a range of different modules to allow dedicated
operation with different cameras.
Densitometer: Specialized
light meter for measuring the density of a negative or transparency (transmission
densitometer) or of a print (reflection densitometer).
Density: A measure
of the opacity of a negative (or filter), or of the brightness (or darkness)
of a print. Density is measured logarithmically as a ratio: starting with a
density of 0.00, a density of 1.0 will transmit or reflect 1/10 as much light,
a density of 2.0, 1/100, and a density of 3.0, 1/1000. One stop (2x) is near
enough D=0.3, and D=0.1 is 1/3 stop.
Depth of Field: Zone
of acceptable sharpness in front of and behind the point on which the camera
is focused. "Acceptable" is a question of personal taste, and the bigger the
degree of enlargement, the smaller the apparent depth of field.
Depth of Focus: Similar
to depth of field, but at the film plane: the acceptable departure from the
point of sharpest focus or focal plane.
Develop: Chemical
process used to convert a film or paper's latent image into visible tones. Also
used to describe the entire process of development and fixing of an image in
an emulsion.
Diaphragm: The mechanical
iris which controls the f/stop of the lens.
Diffraction Limits:
The resolving power of a lens is said to be "diffraction limited" when it reaches
the theoretical limits imposed by the size of the aperture. A rule of thumb
is that the diffraction limited resolution (in line pairs per millimeter) is
equal to 1500 divided by the aperture in use. An f/2 lens is unlikely to reach
the 750 lp/mm limit at f/2 (1500/2), but by f/8 a good lens should be at or
close to its diffraction limit of 188 lp/mm (1500/8); an excellent lens might
well be diffraction limited at f/5.6 (1500/5.6 = 268 lp/mm).
Diffuser: Translucent
panel interposed between a light and a subject to soften the light.
Diopter: A measure
of focal length; 1/f, where f is the focal length in meters. Thus a lens with
a one meter focal length is a one diopter lens; one with a two meter focal length
is 0.5 diopter; one with a 0.5 meter focal length is two diopter. Adding a positive
close-up lens will bring the maximum focused distance (with the lens set at
infinity) to the focal length of the close-up lens: thus a one diopter close-up
lens will mean that a marked infinity focus equates to one meter. Also used
in reference to plus and minus eyepiece correction lenses for near or far-sightedness.
Distortion: A lens
aberration which causes straight lines near the edge of the field to be bent.
If they bend outwards, it is known as barrel distortion; if inwards, pincushion
distortion.
D/log E Curve: A
graph of density (D) against the logarithm of exposure (log E). Used in sensitometry
to compare the sensitivity of different emulsions to light.
Dodge: To lighten
specific areas of a print by decreasing their exposure to light.
dpi: Dots per inch,
a resolutely unmetricated measure of scan details (for scanning pictures into
an electronic system) and of image detail with printers.
Dry Mounting: Method
of mounting a print on a board with a fusible interlayer which both acts as
an adhesive and (in theory) protects the print from any harmful chemicals in
the board, though archival curators today favor unmounted prints. A dry mounting
press is a big, heated press which squeezes the print, the dry mounting tissue,
and the mounting board together, melting the dry mounting tissue, which then
sets to hold the print in place.
DX Coding: System
for automatically setting film speed when the film is loaded into the camera
(35mm only). E-6 : A process used to develop certain types of color transparency
film. EI : Exposure Index. A non-standard film-speed rating, used to indicate
a photographer's "working" film speed when it differs from the manufacturer's
rated ISO.
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Electronic
Shutter: Shutter in which the speed is electronically controlled. The actual
operation of the shutter, the motive power, remains mechanical in most cases,
using the stored energy of a spring to open and close the shutter.
Elements, Lens: The
individual ground and polished glass disks used to construct a lens. See also
Groups.
Emulsion: Strictly,
a misnomer. What photographers call "emulsions" are suspensions in gelatin (which
itself is increasingly often mixed with other binders).
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and digital photography, images, video and film.
Exposure Index: The
working speed at which a particular photographer rates a particular film. It
may or may not match the ISO speed, and unlike the ISO speed it is based on
personal preference rather than on a specified contrast or speed point.
Extension: The distance
from a lens to the focal plane. At infinity, extension is by definition equal
to focal length (except for retrofocus and telephoto lenses). As extension increases,
exposure must be increased to compensate. At up to 1/10 life size, the extra
exposure requirement is trivial, but by the time you are focused at life size,
you need to give two stops extra exposure.
EV: Exposure Value.
Developed in order to simplify numbers used in exposure calculations. Currently
used to describe the range of exposure in which equipment can successfully operate.
Exposure: The amount of light falling on a sensitive material. Controlled with
aperture and shutter speed settings. Exposure Meter : Light Meter. Device used
to measure the amount of light falling on, or reflected from, an object. Extension
Tube: Metal ring attached to a lens that extends the distance from film to lens
so that it may focus at closer than normal distances.
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Factor: Frequently
called Filter Factor. A numerical rating indicating how many times exposure
must be increased to compensate for loss of light caused by the density of the
filter.
Fast: A lens with
a large aperture and high light gathering ability; or a film of high sensitivity
or ISO speed.
Feathering: Using
just the edge of the pool of illumination cast by a lamp, usually to get a soft
effect.
Fiber-Base: Photographic
papers without a plastic coating; see also RC.
Field Camera: Normally,
a (relatively) light, folding, wooden large format camera, though there are
also a few metal field cameras.
Fill: The light(s)
which fill those shadows that are not illuminated by the key light. Film: Translucent
material coated with an emulsion and placed in a camera to record images. Typically
acetate- or plastic-based. Film Holder: Light-tight container used to hold film
for exposure in a view camera. Film Plane: Also called focal plane. The plane
on which a lens focuses a sharp image. Film Speed: Measured with ISO rating,
it is a film's sensitivity to light. Speed increases as sensitivity increases.
Filter: A piece of
optical plastic or glass used on a lens to modify light in a variety of ways
before it reaches the film or paper.
Filter Factor: The
increased exposure needed because a filter absorbs light. Usually quoted as
a factor (1.5x, 2x, 3x, etc.) but may also be quoted as a density: 0.3=1 stop,
0.7=21/3 stops, etc.
Fisheye Lens: A lens
that, by failing to correct barrel distortion at all, allows extreme angles
of view, up to 180°. Full frame fisheyes cover 180° from corner to corner; circular
image fisheyes cover 180° in all directions. Paradoxically, some full frame
fisheye lenses have longer focal lengths than some rectilinear wide angle lenses;
there are fisheyes of 18-15mm for 35mm, and rectilinear lenses of 14mm and 13mm.
Flag/French Flag:
Opaque panel used to shield the subject (or camera) from the direct rays of
a light.
Flare: (1) Degradation
of shadows, or introduction of reflections, caused by light reflected inside
a lens or camera; (2) Bright reflection off a highlight.
Flash: Brief light.
Usually an electronic discharge tube that can be re-used repeatedly, but may
also be expendable (flash bulbs) or even pyrotechnic.
Floating Lens Element:
A lens element (or sometimes group) that moves relative to other elements or
groups as the lens is focused, thereby allowing more sharpness or better control
of aberrations.
Flood, Floodlight:
Lamp throwing a broad, substantially uncontrolled beam of light.
Focal Length: The
distance at which a lens will project an image of a subject at infinity. Thus
a 50mm lens will project an image of a very distant subject onto a plane 50mm
behind the lens.
Focal Plane: The
plane in which the image is brought into focus; the film plane, or the ground
glass on a view camera. The focusing screen of a reflex is commonly referred
to as being in the "equivalent focal plane."
Focal Plane Shutter:
Moving curtain or blade shutter, just in front of the focal plane.
Focus: The point
where light converges to form a clear, sharp image.
Focus Shift: Some
lenses change focus as they are stopped down, though this is not a problem with
most modern designs. Fog: General density in an image caused by unwanted exposure
or chemical activity.
Focusing Spot: A
spotlight where the relative positions of the bulb and reflector, or bulb and
focusing lens, can be varied to control the spread of the light.
Fog: Unwanted density.
Even unexposed grains in an emulsion will develop, and the extent to which they
develop is what affects fog. If very few develop, fog is low; if many develop,
fog is high. Fog may also result from developer oxidation (typically "aerial"
or "dichroic" fog).
Frame: 1. The area
of an image. 2. A single image in a roll of film.
f/stop: The relative
aperture of a lens, measured as a fraction of the focal length. Thus, a lens
with a focal length of 50mm and an aperture of 25mm has a relative aperture
of 50/25 or f/2. This is why a fast lens has an f/number that is lower than
that of a slow lens; if the aperture were 12.5mm, the relative aperture would
be 50/12.5 or f/4. At one time, interchangeable, thin metal plates with holes
of different sizes were used: these were the original "stops."
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Gaffer
Systems: Miniature scaffolding systems which allow you to hold reflectors,
flags, subjects, cameras, and more in position.
Gaffer Tape: Broad,
very sticky fabric tape, usually silver or black. Gets its name from movie industry
lighting technicians (gaffers) who frequently use this tenacious tape to hold
small lights and wiring in difficult locations.
Gamma: A measure
of the contrast of a film or paper. The higher the gamma, the higher the contrast.
G-bar and Contrast Index, or C.I., are refinements of gamma and are invariably
numerically lower.
Gamma: A measure
of the contrast of a film or paper. The higher the gamma, the higher the contrast.
G-bar and Contrast Index, or C.I., are refinements of gamma and are invariably
numerically lower.
Gel: Originally short
for "gelatin"; (1) A colored filter used to modify the color of a light, now
usually made of acetate; (2) A thin, flexible camera filter which may still
be made of cast, dyed gelatin. Most Color Correction (CC) filters are gels.
Gobo: Perforated
flag, though some use "gobo" as a synonymous term for flag. Also known as a
cookie. See also Projection Spot.
Grad: Graduated filter,
clear at one end and tinted or gray at the other.
Gray Card: Card with
precisely controlled 18 percent "mid tone" reflectivity and neutral color balance.
Grain: The silver
halide crystals that compose a photographic emulsion.
Graininess: A subjective
measure of the visible clumping of grains in an emulsion. Different from Granularity.
Granularity: An objective
measure of the size differences of grains; granularity effects visible graininess.
Gray Scale: A scale
of tonal values reproducible in black and white printing.
Ground Glass: A flat
piece of glass that is roughened on one side so that an image focused on it
can be seen. Used as the viewing screen in view cameras.
Group, Lens: Two
(or more) individual lens elements cemented together.
Guide Number: A numerical
valuation for the power of a flash. Used to determine the aperture that will
produce correct flash exposure with a given ISO and distance from flash to subject.
Guide Number = f/stop x Distance.
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Halation:
The tendency of light sources to flare out and acquire a halo. Suppressed by
gray colored film base or by colored anti-halation backings that decolorize
during development.
Halftone: Image reproduced
with black dots (spaced close together for dark areas and far apart for light
areas) that give the illusion of a continuous tone print.
Handheld: The act
of making an exposure with the camera held by hand, rather than mounted on a
tripod.
Hardening Fixer:
Fixer that also hardens the film or paper emulsion. Rarely needed with modern
emulsions except in very soft water areas or at very high temperatures.
H&D Curve: Another
name for the D/log E Curve, after its originators, Ferdinand Hurter and Vero
C. Driffield.
Head (Tripod Head):
The usually removable top of a tripod that allows various movements and adjustments
of the mounted camera. Two main kinds: ball head (a ball and socket type of
joint is used to adjust camera position) and pan head (various adjustments can
be made to move the camera in a specific plane).
Helical Focusing Mount:
Conventional focusing mount in which the lens is moved in and out by a helical
screw thread or cam.
High Key: Picture
with predominantly light tones, though not necessarily lacking in small areas
of dark tones including pure black.
Highlights: Conventionally,
the lightest areas of a print.
HMI: Flicker free
"cold" light source, delivering a great deal of continuous light with minimal
heat. Very expensive.
Honeycomb: Grid which
makes light from a flash (or other source) more directional, like a spot rather
than a flood.
Hydroquinone: A developing
agent, also known as Quinol.
Hypo: Fixer, from
the old name for sodium thiosulphate, "hyposulphite of soda." Modern rapid fixers
often use ammonium thiosulphate as well as "hypo." IF: Internal Focus. A type
of focusing where the lens elements move within the lens barrel, without changing
the external movement or length of the lens.
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Ilfochrome:
Formerly Cibachrome. A type of color printing that produces positive prints
directly from transparencies.
Images: A reproduction
or imitation of the form of a person or thing produced by an optical device
( as a lens ) or an electronic devise.
Incident Light Metering:
Measuring the light falling on the subject, rather than the light reflected
from it.
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Infinity: The farthest
position on the distance scale of a lens.
Infrared (IR): Literally
"below red," light which is invisible to the naked human eye but which can be
recorded on specially sensitized films. Some creatures (such as bees) can see
IR light, and even humans can see light beyond about 700nm (nanometers) through
an "IR" filter if they are given time to acclimatize; it is perceived as a very
deep, faint red.
IS: Image Stabilization.
Mechanism within a lens that helps reduce blurring due to minor camera motion.
ISO Speed: A standardized,
scientific determination of the speed of a film. Claimed ISO speeds are normally
entirely accurate, but this does not mean that they are the only speed you can
use: with negative films in particular, you may prefer the effect you get with
higher or (more usually) with lower working speeds.
Instant Film: A film
that contains the necessary chemicals for development, so it can be processed
right after exposure.
Intensifier: Chemical
treatment for adding density to an underexposed or underdeveloped negative or
print. With prints, it is normally easier to re-make the print; with a negative,
the loss of quality is normally so bad with all but the largest formats that
the results are unacceptable.
Interchangeable Lens:
A lens that can be removed from a camera and replaced with a different lens.
Internal Focusing (IF):
System of focusing a lens in which instead of moving the whole lens to and fro,
only some elements or groups are moved, thereby changing the effective focal
length.
Inter-Neg: A negative
that is made from a transparency image in order to produce standard type-C color
prints.
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Joules:
Another name for watt seconds.
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K-14:
The chemistry used to process Kodachrome film.
Key: The main light;
the one that casts the shadows.
Kelvin Scale: Used
to measure and define the color temperature of different light sources
Kilowatts (K): One
kilowatt is 1000w. Big tungsten lamps are frequently referred to as "2K," "5K,"
etc.
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Large
Format: Normally, cut film of 4x5" and above, though smaller format cameras
can be similarly constructed and quarter plate (31/4x41/4") may be regarded
as the last medium format or the first large format..
Latent Image: An
exposed film looks identical to an unexposed film, but it has a "latent image"
which can be brought out by development. Development centers may consist of
only a few individual atoms.
Latitude: The range
of exposure (+/-) in which a photographic emulsion will produce a usable image.
Leaf Shutter: Between
lens shutter, where thin metal leaves open and close to effect the exposure.
The shutter is normally positioned as close to the diaphragm as possible.
Lens: A piece (or
multiple pieces) of optical glass that is shaped to focus an image.
Lens Shade (Lens Hood):
An attachment to the front of a lens that prevents extraneous light from shining
directly onto the lens and producing flare.
Light Brush: An enclosed
light source to which is attached a flexible "light pipe" which allows the photographer
to direct the light as if he were "painting" with it. Can be approximated with
a torch (flashlight).
Light Meter (Exposure
Meter): A device that measures luminance and luminance, allowing the photographer
to determine the correct exposure.
Lighting Ratio: The
ratio between the key and fill lights.
Light-Tight: Refers
to any container that is absolutely dark inside, allowing no unwanted light
to penetrate.
Lith Film: Very high
contrast film, which gives pure blacks and whites and no grays. Lith paper is
a very high contrast paper, though it does normally give some grays with all
but the contrastiest negatives.
Luminance: The light
reflected by, or emanating from, a surface.
Long Lens: Any lens
with a focal length longer than standard for a given camera format.
Low Key: Picture
with predominantly dark tones, though not necessarily lacking in areas of light
tones, including pure white.
Lux, Lux Second:
One lux is the light from one standard candela (akin to a standard candle) at
one meter. A lux second, also known as a meter candela second, is one lux acting
for one second.
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Macro:
Strictly, photography at life-size or larger. In practice, often used to mean
"close-up" (down to about 1/3 or even 1/5 life-size) or in some cases nothing
more than "closer than usual".
Macro Lens: A lens
designed to produce very high sharpness when focused up-close; a lens that produces
a ratio of 1:1 when used up close.
Manual Exposure:
A mode of camera operation in which all exposure settings are determined and
set by the photographer.
Matrix Metering: (Also
called Evaluative Metering and Honeycomb Metering.) Advanced TTL metering system
that uses simultaneous readings from multiple image areas to determine the correct
exposure.
Medium Format: Normally,
a camera taking roll film (typically 120/220 but also 70mm and a range of obsolete
roll film sizes), though there are arguably "medium format" cut film sizes such
as 21/4x31/4", 21/2x31/2", 6.5x9cm, and possibly even quarter plate (31/4x41/4").
The most usual formats on 120 films are 645 (15-on or 16-on, around 42x56mm),
6x6cm or 21/4 square (12-on, around 56x56mm), 6x7cm (10-on, around 56x70mm)
and 6x9cm or 21/4x31/4" (8-on, around 56x84mm), though nominal 6x8cm, 6x12cm,
6x17cm, and even 6x24cm formats also exist.
Metol: A developing
agent. The "M" in MQ developers.
Middle Gray: A standard
gray tone that reflects 18 percent of light falling on it. When a meter determines
exposure, it assumes the subject it sees is middle gray.
Mid Tone: In common
usage, a "mid gray" of approximately 18 percent reflectivity. Because the eye’s
perception of density is logarithmic, a tone with 50 percent reflectivity (which
you might think was a mid tone) will in fact look very dark. See also Zone System.
Monobloc: (also monoflash)
Flash head with built-in power supply.
Monopod: A single
leg (as in a tripod leg) with a mounting bracket used to steady cameras. Typically
used when a tripod is impractical.
Monorail: Large format
camera (usually, though there are medium format examples) constructed on an
"optical bench" principle with front and rear standards on a rail.
Movements: The ability
to move the lens and the film plane parallel to one another (rise, fall, cross,
or shift movements) or out of parallel with one another (swing or tilt movements).
They are used to control apparent perspective, image shape, and focus. Normally
found only on large format cameras, there are a few medium format examples and
the KI Monobar was a 35mm monorail.
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Negative:
Film that produces an image with brightness levels opposite of the actual scene
(black is white, etc.) and must be printed to produce a positive image.
Neutral Density Filter:
Neutral gray filter which reduces the intensity of light without affecting its
color. May be described in filter factors (2x, 4x, 10x, etc.) or in densities
(0.3, 0.6, 1.0, etc.).
Nodal Point: In the
real world, a lens has a finite thickness. Its focal length must be measured
from somewhere inside the lens, and this is the nodal point. Again in the real
world, because we are dealing with "thick" multiple lens systems, there are
two nodal points which may be some distance apart, and reversing the lens may
drastically affect the distance from the lens to the focal plane.
Normal Lens: A lens
with a focal length approximately the same as the diagonal measurement of the
film being used. This produces an image that approximates the same angle of
view and perspective of the human eye.
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Open
Up: To increase the size of the aperture by adjusting the f/stop to a smaller
number.
Optical Axis: An
imaginary line drawn straight through the middle of a lens, parallel with the
direction of the light; the lens is radially symmetrical about the optical axis.
Overexpose: To give
more than the normal exposure to film or paper.
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Pan:
To follow the horizontal movement of an object.
Panoramic: A long
thin picture, typically at least twice as long as it is high. Some people reserve
the term "panoramic" for images produced by swinging lens or moving film cameras,
while others also apply it to any picture of appropriate aspect ratio.
Parallax: The difference
in point of view that occurs when the taking lens is separate from the viewing
lens.
PC: Stands for "Perspective
Control" or (less accurately) "Perspective Correction," as achieved with movements
or with a shift lens.
PC Connector: Synch
Cord. The electrical cord that connects an off-camera flash with the camera
so that they may synchronize.
Perspective: The
apparent size and depth of objects in a scene, related to point of view.
pH: A measure of
acidity or alkalinity. pH7 is neutral; lower numbers indicate increasing acidity,
while higher numbers indicate increasing alkalinity. pH control is an essential
aspect ophotographic chemistry, and one which is often neglected by amateur
chemists.
Phenidone: A developing
agent, less allergenic than metol, which it replaces at the ratio of about one
part phenidone to 10 parts metol. The "P" in "PQ" developers.
Photoflood: Tungsten
lamp delivering a great deal of light at 3400K, but with a correspondingly short
life.
Plane of Focus: The
plane in which objects in a scene are critically sharp.
Point and Shoot:
(Subjective term.) Typically automatic or with minimal adjustable controls,
these cameras are used for easy photography. The name comes from the idea that
the cameras are so simple the photographer need only point and shoot.
Polarizing Filter:
Filter that allows control of reflections under certain circumstances.
Polaroid Back: Some
35mm cameras, most professional medium format cameras, and almost all 4x5" cameras,
can be fitted with Polaroid instant picture backs.
Portly Shutterbug:
The official, adorable mascot and guide of guide to the wonderful new portal
showcasing anything, everything and everyone within the world of traditional
and digital photography, images, video and film...known as www.shutterport.com
Portrait: Apart from
the obvious meaning, a "portrait" image is a rectangular picture with the longer
dimension on the vertical axis. See also Landscape.
Portrait Lens: Normally,
a lens with a focal length of around 1.5x-2x the focal length of the standard
lens (i.e. of the negative diagonal). Also used as soft focus lenses.
Positive: Any photographic
image with tones corresponding to the subject. The opposite of a negative.
Primary Colors: The
"additive" primaries are Red, Green, and Blue (RGB); the subtractive or complementary
primaries, which are complementary to RGB, are Cyan, Magenta, and Yellow (CMY).
For photomechanical reproduction, black is normally added, giving CMYK (K from
blacK: B for black could be confused with B for blue).
Print: A photographic
image, usually a positive, on paper.
Processing: The act
of chemically developing and fixing an image on film or paper.
Program Mode: An
automatic exposure mode in which the camera adjusts all aspects of exposure.
Projection Spot:
Spot which can cast an image, like a slide projector. The image for projection
may be of film or (for durability and heat resistance) of perforated metal,
in which case it is often called a gobo.
Proof: A test print
made for evaluation purposes, whether for content or technical quality.
Push: To expose film
at a faster speed rating (EI) than that specified by the manufacturer (ISO),
then compensated for the underexposure by overdeveloping.
Pyro, Pyrogallol, Pyrogallic
Acid: A developing agent.
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Quinol:
Another name for hydroquinone; the "Q" in "MQ" developer.
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Rangefinder:
A device for determining distance. May be coupled to the focusing movement of
a camera, so that when the rangefinder is in focus, so is the lens. Traditional
rangefinders were optical/mechanical devices; today, the same term may arguably
be applied to those autofocus systems which do not rely on the image formed
by the taking lens.
RC: "Resin Coated"
photographic papers, effectively paper with a polyethylene coating to prevent
water absorption by the paper base. Washing is much faster than with fiber-base
but permanence is probably not quite as great, and for some applications RC
does not look as good, though many people cannot actually tell the two kinds
of paper apart visually, without handling them.
Reciprocity Failure:
Very long or very short exposure times may require additional exposure, a "failure"
of the normal law that you can compensate for changes in light intensity by
changing the exposure time. Color films may also require additional filtration.
Rectilinear Wide Angle:
Term sometimes used to describe extreme wide angle lenses which cover angles
of 90° and more without the barrel distortion associated with fisheye lenses.
Reducer: Chemical
treatment to lighten an overexposed (dark) negative or print. With prints, it
is normally easier to re-make the print; with a negative, the loss of quality
is normally so bad with all but the largest formats that it is unacceptable.
Local reduction (with ferricyanide or Farmer’s Reducer) is used by many master
printers for selective lightening of small areas of the print.
Reflector: (1) The
surround to a light source, which reflects the light onto the subject; (2) A
reflective panel, usually white, silver, or gold in color, used to bounce natural
or artificial light into the shadow areas of a scene, especially portraits.
Reflex: A camera
in which the image is reflected onto the viewing screen. The Single Lens Reflex,
or SLR, uses a "flipping mirror" between the taking lens and the film; with
the mirror in the down position, the image is reflected onto the viewing screen,
and with the mirror in the up position, it passes straight to the film. A Twin
Lens Reflex, or TLR, has separate viewing and taking lenses, and a fixed mirror
behind the viewing lens.
Reflected-Light Meter:
A light meter that measures luminance, the light reflected off an object.
Refractive Index (R.I.):
When light moves from one medium to another, as from air to glass (or glass
to air, or water to air, etc.), it is "bent": as is familiar from the "bent"
appearance of a stick held half in and half out of water. R.I. is a measure
of how much the light is bent. Media with a high R.I. bend the light more than
media with a low R.I., and the R.I. of different glasses varies widely. The
importance of R.I. in lens design is obvious.
Reciprocity: An uncontrollable
shift in color caused by to long or to shot an exposure on film not Designed
for said exposure.
Resolution: A subjective
valuation of the detail-recording ability of photographic materials.
Resolving Power:
A substantially meaningless but easily understood measure of how much detail
a given lens or film can capture, measured in line pairs per millimeter (lp/mm).
It is meaningless in absolute terms because it depends on contrast and other
test conditions, so one person’s figures can rarely be compared usefully with
another’s. It is, however, useful in comparative terms, when the same test is
applied to a number of lenses (or films, or lens/film combinations). In the
real world, on the film resolutions of up to about 100 lp/mm are fairly easily
obtained with good lenses on 35mm and even 120 cameras.
Restrainer: An additive
(in a developer) that slows development. The main purposes of restrainers are
to reduce fog and to affect image color.
Retouching: Modifying
a correctly recorded image, whether by traditional methods (pencil, airbrush,
etc.) or electronically. Should be distinguished from spotting or "finishing,"
where the only aim is to clean up flaws and dust marks introduced by the photographic
process.
Reversal: A chemical
process that changes a negative image into a positive, usually via a second
development stage. The actual reversal step may be chemical, or by a second
exposure to light.
Reversal Film: Transparency/Chrome.
Film that produces a positive image upon exposure and development.
Ring Flash: Flash
where the discharge tubes are concentric with the lens, to allow shadowless
lighting.
Roll Film: Any film
that is packaged in rolls (typically for multiple exposures) rather than single-exposure
sheets. Usually refers to medium formats, not 35mm.
Rule of Thirds: A
"rule" of composition which says that a picture element will always attract
more attention if it is on or near the intersections of a tic-tac-toe board
(hence "thirds") which is mentally superimposed on an image.
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Safelight:
Light of a color to which a particular material is insensitive, or so weakly
sensitive that it may be handled under that light for a few minutes.
Scheimpflug Rule:
A useful rule when using camera movements is that when the planes of the subject,
the lens panel, and the image are made to coincide at a single line, everything
will be in focus.
Scrim: Fabric used
to reduce the intensity of a light. May also act as a diffuser.
Seamless (paper):
Wide rolls of paper, used as background material.
Sensitization: Silver
halides (on which all conventional photography is based) are sensitive only
to blue, indigo, violet, and ultraviolet light. By adding appropriate dyes to
the emulsion, this sensitivity can progressively be extended to green (orthochromatic
or ortho films), to orange and red (panchromatic or pan films), to deep red
and even the near infrared (extended red pan), and finally to infrared. Diagrams
that show the effects of the different dyes are generally referred to as spectral
sensitization diagrams; they are drawn from spectral wedge images which show
the same thing.
Sensitometry: The
science of measuring the response of films and papers to light.
Set: By analogy with
a "stage set," a built scene, or environment.
Sharpness: Subjective
description of an image's focus and resolution.
Sheet Film: Film
that is used as individual, single-exposure flat pieces.
Shift Lens: A lens
which can be moved up, down, or sideways relative to the optical axis. Most
often used to avoid the "falling over backwards" effect when photographing buildings.
Short Lens: Term
describing a wide-angle lens (a lens whose focal length is shorter than the
diagonal measurement of the film used).
Short Stop or Stop Bath:
Acidic rinse after development which arrests the action of the (alkaline) developer.
The traditional acid was acetic, but modern odorless fixers use citric. Short
stops are far from essential; their main purpose is to extend the life of the
fixer somewhat.
Shutter: A camera
mechanism that opens and closes to allow light to enter the camera for a specific
amount of time in order to expose the film.
Shutterbug: Someone
who enjoys taking photographs and using cameras. The last name of Portly the
official mascot and guide for www.shutterport.com.
Shutterport: The
epicenter aggregator, infomediary and facilitator (B2B and B2C) for all products,
services and personnel in the world of images. www.shutterport.com begins with
photo sharing and adds a thousand additional features and functions for the
use and benefit of its members and visitors.
Shutter Priority:
A mode of automatic exposure by which the photographer manually adjusts the
shutter speed, and the camera adjusts the aperture accordingly to produce a
normal exposure.
Silhouette: A scene
in which the background is brighter than the subject, producing a detail-less,
shadowed subject.
Silver Halide: The
light-sensitive parts of a photographic emulsion; compounds of silver chloride,
silver bromide and silver iodide.
Silver Speed: Color
and chromogenic films can be thought of as having two speeds: the inherent or
silver speed, which is their speed if developed normally in a black and white
developer, and the dye speed, which results from the dyes given off during color
development. Dye speeds can be quite a bit higher than silver speeds, so a film
with a dye speed of (say) ISO 1000 might have a silver speed which is a stop
or more lower (ISO 500 or below).
Slave: A flash which
fires when another flash is fired, triggered by a light-sensitive cell. The
response is sufficiently rapid that the flash is effectively instantaneous.
Slide: A transparency
that is mounted for insertion into a projector.
Slow: Term referring
to: 1. photographic emulsions that are not very light-sensitive, 2. lenses whose
maximum aperture are not very large, 3. long shutter speeds.
SLR: Single Lens
Reflex camera. One lens acts as both viewing and taking lens.
Snoot: Tubular or
conical attachment to control the spread of light from a lamp.
Softbox: Large, diffuse
light, usually with electronic flash as the light source.
Soft Focus: Not the
same as "out of focus." A purposely built soft focus lens normally features
under corrected spherical aberration, so that a point of light is represented
with a halo around it. Soft focus attachments (often incorrectly called "filters")
duplicate this effect with more or less success.
Spectrum: The conventional
spectrum or rainbow of "red, orange, yellow, green, blue, indigo, violet" is
essentially culturally conditioned; you could equally well split it into four
(red, yellow, green, blue, with red-yellow to describe orange, and "blue" doing
duty for blue, indigo, and violet), or into 10 or more (with deep red as well
as red, yellow-green and green-blue as well as yellow/green/blue, and so forth).
Specular Reflections:
Strictly, reflections as in a speculum or mirror, which cannot be controlled
by the use of a polarizing filter. In popular usage, any highlight which "burns
out" to a pure white because of flare or because it exceeds the recording range
of the film.
Speed Point: The
level of exposure used to determine the sensitivity of a film. For the ISO speed,
it is based on the exposure (in lux seconds) required to give a density of 0.10
above film base plus fog.
Spherical Aberration:
A lens aberration resulting from the use of spherical or common curves; rays
passing through the outer area of the lens are brought to a different focus
from those passing through the center.
Spill: Light which
"spills" from the main sources. Sometimes it can be used as general illumination
or fill; at other times it needs to be controlled with flags.
Spot Meter: A reflected-light
meter with a very small angle of view, used to measure brightness of a small
portion of a scene.
Stop: An aperture
setting, or shutter speed setting, on a lens or camera. Also, a change in exposure
by a factor of two.
Stop Down: To decrease
the size of an aperture. The opposite of opening up.
Strobe: Loosely refers
to an electronic flash, or any light source that emits light in very short bursts.
Synch Cord: PC Connector.
The electrical cord that connects an off-camera flash with the camera so that
they may synchronize.
Synchronize: To cause
two events to occur simultaneously (as in a shutter opening and a flash firing).
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Telephoto
Lens: A lens that magnifies an image and produces a narrowed angle of view.
As the focal length increases, the magnification increases and the angle of
view decrease.
Tone: The lightness
or darkness of a particular area. Also, to color a print by immersion in a chemical
solution.
Transparency: Film
in which the final image is positive. Often used interchangeably with chrome,
positive and slide.
Tripod: A three-legged
stand used to hold a camera steady during exposure.
TTL: Through The
Lens. A type of scene metering in which the camera accepts information directly
through the lens. (For example, a TTL light meter or TTL flash meter.)
Tungsten Film: Often
called Type B. Film that is balanced to record color correctly under tungsten
lighting.
Tungsten Light: Light
that is roughly 3200 degrees Kelvin in color temperature.
Type C Print: The
standard form of printing color negatives into positive prints. Commonly called
a "C-Print."
Type R Print: A method
for printing transparencies into positive prints, without making an inter-neg.
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Ultraviolet
Light: Light that is just beyond violet on the visible spectrum.
Underexpose: To give
less exposure than normal. Produces less density in negatives, more density
in transparencies.
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Value:
The relative lightness of an area. Low values are dark, high values are light.
View Camera: A camera
with movements in which the taking lens forms an image directly on a ground-glass
viewing screen. A film holder is inserted in front of the ground glass for exposure.
Also called large-format camera (typically producing images 4x5 inches.
Viewfinder: A small
window on a camera through which the scene is viewed.
Viewing Lens: The
lens on a camera through which the photographer's eye sees the subject.
Viewing Screen: The
ground-glass element in a camera on which the subject is viewed.
Vignette: An image
with underexposed or overexposed (lighter or darker) edges.
Visible Spectrum:
The electromagnetic spectrum of visible light; red, orange, yellow, green, blue,
indigo, violet.
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Warm:
Reddish colors that are commonly associated with objects that are warm.
White Light: Light
containing equal amounts of the primary additive colors of light. The human
eye sees this light as colorless.
Wide-Angle Lens:
A lens whose focal length is shorter than the diagonal measurement of the film
used.
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Zone
System: A method of planning film exposure and development to achieve precise
control of tones in a print. Pioneered by photographers such as Ansel Adams
and Minor White.
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