20.01.10
A-Z of Photography
Agfa
Agfa-Gevaert is a European multinational corporation that develops, manufactures and distributes analogue and digital products and systems for the making, processing and reproduction of images.
Albumen print
The albumen print, also called an albumen silver print, was invented in 1850 and was the first commercially exploitable method of producing a photographic print on a paper base from a negative. It used the albumen found in egg whites to bind the photographic chemicals to the paper, and became the dominant form of photographic positives from 1855 to the turn of the last century.
Ambient light
This is a term used by photographers to refer to the light surrounding a subject or scene, and all light not provided by the photographer. Levels of ambient light are most frequently considered relative to additional lighting used as fill light, in which case the ambient light is normally treated as the key light. In some cases, ambient light may be used as a fill, in which case additional lighting provides the stronger light source, for example in bounce flash photography. The relative intensity of ambient light and fill light is known as the lighting ratio – an important factor in calculating contrast in the finished image.
Angle of view (field of view)
Angle of view describes the angular extent of a given scene that is imaged by a camera. It is important to distinguish the angle of view from the angle of coverage, which describes the angle of projection by the lens onto the focal plane. For most cameras, it may be assumed that the image circle produced by the lens is large enough to cover the film or sensor completely. If the angle of view exceeds the angle of coverage, however, then vignetting will appear in the resulting image.
Anti-static agent
An anti-static agent is a compound used for the treatment of surfaces such as screens, lenses and mirrors to reduce or eliminate build-up of static electricity generally caused by the triboelectric effect. Its role is to make the surface or the material itself slightly conductive, either by being conductive itself, or by absorbing moisture from the air, so some humectants can be used. The molecules of an anti-static agent often have both hydrophilic and hydrophobic areas, similar to those of a surfactant; the hydrophobic side interacts with the surface of the material, while the hydrophilic side interacts with the air moisture and binds the water molecules.
Aperture
1. The unit of measurement that defines the size of the opening in the lens that can be adjusted to control the amount of light reaching the film or digital sensor. The size of the aperture is measured in F-stops.
2. A software program for Mac OS X developed by Apple. designed to assist professional photographers in post production work. It was announced at a New York media event on October 19 2005 and released on November 30 the same year. Aperture 2.0 was released on February 12 2008.
Arca
The Arca view camera is a type of camera first developed in the era of the daguerreotype and still in use today, though with many refinements. It comprises a flexible bellows that forms a light-tight seal between two adjustable standards, one of which holds a lens, and the other a viewfinder or a photographic film holder. The bellows is a flexible accordion-pleated box, which encloses the space between the lens and film, and has the ability to flex to accommodate the movements of the standards. The front standard is a board at the front of the camera which holds the lens and, usually, a shutter. At the other end of the bellows, the rear standard is a frame that holds a ground glass, used for focusing and composing the image before exposure, which is replaced by a holder containing the light-sensitive film, plate or image sensor for exposure. The front and rear standards can move in various ways relative to each other, unlike most other types of camera, giving control over focus, depth of field and perspective.
Archival paper
Acid-free paper is paper that has a neutral or basic pH (7 or slightly greater) and is made from any cellulose fibre that has had active acid pulp eliminated during its production. This acid-free paper addresses the problem of preserving photographic prints for long periods.
ASA
This is the abbreviation that denotes film speed and is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system for digital cameras. Relatively insensitive film, with a correspondingly lower speed index, requires more exposure to light to produce the same image density as a more sensitive film, and is thus commonly termed a slow film. Highly sensitive films are correspondingly termed fast films. A closely related ISO system is used to measure the sensitivity of digital imaging systems. In both digital and film photography, the reduction of exposure corresponding to use of higher sensitivities generally leads to reduced image quality.
Asahi Pentax
The company was founded in 1919 at a shop in a suburb of Tokyo, and began producing spectacle lenses. In 1938 it changed its name to Asahi Optical Co Ltd, and by this time it was also manufacturing camera/cine lenses. In the lead-up to the Second World War, Asahi Optical devoted much of its time to fulfilling military contracts for optical instruments.
Batch processing
Batch processing describes the execution of a series of programs on a computer without manual intervention.
A program takes a set of data files as input, processes the data, and produces a set of output data files. This operating environment is termed as ‘batch processing’ because the input data is collected into batches on files and are processed in batches by the program.
Beaton, Cecil
Beaton is best known for his fashion photographs and society portraits. He worked as a staff photographer for Vanity Fair and Vogue magazines in addition to photographing celebrities in Hollywood. Over the course of his career, he employed both large-format cameras, and smaller Rolleiflex cameras. Beaton was never known as a highly skilled technical photographer, and instead focused on staging a compelling model or scene and looking for the perfect shutter-release moment.
Bessa
The Bessa family of cameras is manufactured in Japan by Cosina as a revival of the Voigtländer brand name. All the Cosina Voigtländer Bessa models have a double focal plane shutter with two sets of curtains to prevent damage by the sun. Shutter speeds range from 1 to 1/2,000s and bulb (B), with flash sync at 1/125s on hot shoe or PC terminal. They all have TTL exposure metering, and manual exposure; the recent R2A and R3A also have an aperture priority automatic mode.
Billingham
M Billingham & Co was formed in 1973 by its present owners and is still a family business. Conceived, designed and made in the UK, Billingham bags reflect an English preoccupation with excellence and attention to detail. The company's transition from a manufacturer of fishing bags to one of camera bags came about in 1978 when Martin Billingham, a keen photographer himself, discovered that the fishing bags he made were being used by New York photographers. So popular were the first models that, within a year, almost all production had switched to camera bags.
Black-and-white papers
Black-and-white papers are coated on a small range of bases; baryta-coated paper, resin-coated paper or polyester.
Blemish tool
A tool used in Photoshop to remove skin blemishes, marks and spots within an image.
Blur
A term for areas of the image that show movement or a shallow depth of field.
Broncolor
Bron Elektronik manufactures flash equipment and is based in Switzerland. The company makes the Broncolor and Visatec lines of strobes. The Broncolor line includes studio systems with separate power packs and heads, as well as monolights; Visatec concentrates on monolights and also markets battery packs for portability.
Bowens
Bowens first started manufacturing lighting equipment for photographers. The first flash bulb units were produced in 1947, but by 1950 the company had already started to produce the first electronic studio flash systems. Until the 1960s, studio flash systems were large and cumbersome, requiring bulky power generators to power the flash heads, connected by large cables. In 1963 it invented the first electronic studio flash unit with its power source built into it. This became known as a monobloc (sometimes monolight), which is now an industry standard piece of equipment. In 1968 it produced an update to the Monobloc: the Monolite 400 and later products such as
Quad, Prolite and Esprit have also proved popular among photographic professionals. Today, the company continues to produce studio flash systems and photographic accessories from its factory in Clacton-on-Sea, England.
Bounce
The process of using any form of surface – usually white, silver or gold – to redirect light from its original source.
Bokeh
Bokeh is a photographic term for blur, most often seen in images with a shallow depth of field.
Burning in
The term used to refer to the darkening of a particular area of an image for aesthetic reasons – most commonly to adjust over-exposed highlight areas.
Bromide paper
Photographic paper with pure silver bromide emulsions that are sensitive and produce neutral black or 'cold' blue-black image tones.
Book
The term used in the commercial photography world to describe a photographer’s portfolio.
Bourdin, Guy
Controversial and influential. This French fashion photographer took conceptual photography into previously unchartered waters while also foreseeing today’s Photoshop aesthetic 30 years ago. www.guybourdin.com
Box camera
With the exception of the pin hole camera, a camera in its simplest form. It has a simple optical system. It usually lacks a focusing system as well as control of aperture and shutter speeds. This makes it suitable for daylight photography only.
Bracketing
This is the technique of taking several shots of the same subject using different exposure settings either side plus or minus of the correct exposure settings. Bracketing is useful and often recommended in situations that make it difficult to obtain a satisfactory image with a single shot, especially when a small variation in exposure parameters has a comparatively large effect on the resulting image.
Brush tool
A tool used in digital post production to feather detail, replace tones and extend areas and textures.
Bulb exposures
When the bulb is set, the shutter stays open while you hold down the shutter button fully, and closes when you let
go of the shutter button. This is bulb exposure and is useful for night photography, fireworks and subjects requiring long exposures.
Bytes
Is a unit of information storage. It is an ordered collection of bits, with each bit denoting a single binary value of 1 or 0. The byte is the basic addressable element in many computer architectures. The size of a byte is hardware dependent, but the 8-bit byte has become a de facto standard today.
Calotype print
The sensitive element of a calotype is silver iodide. With exposure to light, silver iodide decomposes to silver, leaving iodine as a free element. Excess silver iodide is washed away after oxidising the pure silver with a second application of gallo-nitrate. As silver oxide is black, the resulting image is visible. Potassium bromide is then used to stabilise the silver oxide. The salted paper's sensitive element is silver chloride formed when the salt (sodium chloride) reacts with silver nitrate. Silver chloride decomposes when in contact with light forming silver and chlorine evaporates. Excess silver chloride is washed out of the paper and the silver oxidises in contact with gallo-nitrate. The silver oxide is stabilised on the paper with hypo. Silver chloride makes better prints because it is less sensitive to temperature.
Camera obscura
The camera obscura (Latin for ‘dark room’; ‘darkened chamber’) is an optical device that projects an image of its surroundings on a screen, and was one of the inventions that led to photography. The device consists of a box or room with a hole in one side. Light from an external scene passes through the hole and strikes a surface inside, where it is reproduced upside-down, but with colour and perspective preserved. The image can then be projected onto photographic paper.
Canon
Established in 1937, Canon has grown into a global company operating in a diverse range of markets, including all forms of imaging equipment. With a global workforce of more than 160,000 people in close to 245 companies, Canon is one of the most widely recognised companies in the world. Its continued development within camera technology means that it has remained at the forefront of the photographic industry.
CF Card
CompactFlash (CF) is a mass storage device, typically using flash memory in a standardised enclosure. The format was first specified and produced by SanDisk in 1994 and is now produced by a variety of manufacturers from 2GB to 64GB.
Clone tool
A tool used in post production to copy and repeat an area of an image to extend or replace a specific area.
Cokin
Cokin is a French manufacturer of optical filters.
Composition
A term used to describe the aesthetic choices made by a photographer when deciding what to include within the photographic frame.
Contact sheet
A contact print is a photographic image produced from a film, usually a negative, occasionally from a film positive. The defining characteristic of a contact print is that the photographic result is made by exposing through the film original onto a light-sensitive material pressed tightly to the film. A digital contact follows a similar format to a traditional contact sheet but will be produced within a digital software package. Contact sheets are used to show a large sample of images at reduced size including image numbering details.
Conversion
The process of converting an image file from one format to another. For example, from RAW to TIFF or JPEG.
Copyright
Copyright is a form of intellectual property that gives the author of an original work exclusive rights for a certain time period in relation to that work, including its publication, distribution and adaptation, after which time the work
is said to enter the public domain. Copyright has been internationally standardised, lasting between 50 and 100 years from the author's death, or a shorter period for anonymous or corporate authorship. Some jurisdictions have required formalities to establish copyright, but most recognise copyright in any completed work, without formal registration. Generally, copyright is enforced as a civil matter, though some jurisdictions do apply criminal sanctions.
Cosina
Cosina Co Ltd is a designer and manufacturer of cameras and lenses, and a glassmaker, based in Japan. Having obtained the rights to the name Voigtländer from Ringfoto in Germany, Cosina introduced a Voigtländer 15mm f/4.5 and 25mm f/4 lens (neither of them rangefinder-coupled) and the Voigtländer Bessa L body in 1999. It quickly followed with a wider range of cameras (starting with the Bessa R, with viewfinder and rangefinder; and the Bessa T, with rangefinder but no viewfinder); and a set of lenses including the Heliar 12mm f/5.6 lens, which, on its introduction, was the widest rectilinear lens ever marketed for still photography. The name Cosina now appears (conspicuously) on lenses for various SLR mounts, and less conspicuously on a widening range of cameras and lenses with the Voigtländer brand. Cosina manufactured a Rollei-branded rangefinder camera, and is acknowledged to have manufactured (and to have helped design) an Epson digital rangefinder camera as well.
Cropping
The art of resizing an image for aesthetic effect.
Curves
In image editing, a curve is a remapping of image tonality, specified as a function from input level to output level, used as a way to emphasise colours or other elements in a picture. Curves can usually be applied to all channels together in an image, or to each channel individually. Applying a curve to all channels typically changes the brightness in part of the spectrum. The software user may, for example, make light parts of a picture lighter and dark parts darker to increase contrast. Applying a curve to individual channels can be used to stress a colour. This is particularly efficient in the Lab colour space due to the separation of luminance and chromaticity, but it can also be used in RGB, CMYK or whatever other colour models the software supports.
Daguerreotype
An early type of photograph, developed by Louis Daguerre, in which the image is exposed directly onto a mirror-polished surface of silver bearing a coating of silver halide particles deposited by iodine vapour. In later developments, bromine and chlorine vapours were also used, resulting in shorter exposure times. It is a negative image, but the mirrored surface of the metal plate reflects the image and makes it appear positive when the silvered surface has a dark ground reflected into it. Thus, daguerreotype is a direct photographic process without the capacity for duplication.
Deardorff
Manufacturers of wooden-construction, large-format 8"x10" and larger bellows view cameras from 1923 to 1988. Various models were constructed and used mostly by professional photographic studios.
Decisive moment
The term coined by the great photographer Henri Cartier- Bresson to describe the right moment to take a photograph.
Depth of field
The depth of field (DoF) is the portion of a scene that appears acceptably sharp in the image. Although a lens can precisely focus at only one distance, the decrease in sharpness is gradual on each side of the focused distance, so that within the DoF, the unsharpness is imperceptible under normal viewing conditions.
Digital noise
Is the random variation of brightness or colour information in images produced by the sensor and circuitry of a scanner or digital camera. Image noise can also originate in film grain and in the unavoidable shot noise of an ideal photon detector.
DPS (double page spread)
An editorial term used to describe how a photograph will be used.
DSLR
A digital single-lens reflex camera (digital SLR or DSLR) is a digital camera that uses a mechanical mirror system
and pentaprism to direct light from the lens to an optical viewfinder on the back of the camera.
Duotone
Is a halftone reproduction of an image using the superimposition of one contrast colour halftone (traditionally black) over another colour halftone. This is most often used to bring out mid tones and highlights of an image. The most common colours used are blue, yellow, brown and red.
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