Photography Glossary

Glossary

Aliasing	The display of a digital image where a curved line appears jagged due to the square pixels.
Ambient light	The natural or artificial continuous light that exists before the additional lighting is introduced.
Analyse/Analysis	To examine in detail.
Anti-aliasing	The process of smoothing the appearance of a curved line in a digital image.
Aperture	A circular opening in the lens that controls light reaching the sensor.
Backlit	A subject illuminated from behind.
Balance	A harmonious relationship between elements within the frame.
Bit	Short for binary digit, the basic unit of the binary language.
Blurred	An image or sections of an image that are not sharp. This can be caused through inaccurate focusing, shallow depth of field or a slow shutter speed.
Bounced light	Lighting that is reflected off a surface before reaching the subject.
Bracketing	Over- and underexposure either side of a meter-indicated exposure.
Byte	8 bits. The standard unit of binary data storage containing a value between 0 and 255.
Cable release	A cable that allows the shutter to be released without shaking the camera when using slow shutter speeds.
Camera shake	Blurred image caused by camera movement during the exposure.
CCD	Charge-coupled device. A type of image sensor used in digital image capture.
Channels	A method of separating a digital color image into primary or secondary colors.
Cloning tool	A tool used for replicating pixels in digital photography.
Close down	A term referring to the action of making the lens aperture smaller.
Close-up lens	A one-element lens that is attached to the camera’s lens allowing the image to be focused when the camera is close to a subject.
CMYK	Cyan, Magenta, Yellow and blacK. Inks used in four-color printing.
Composition	The arrangement of shape, tone, line and color within the boundaries of the image area.
Compression	A method of reducing the file size when a digital image is closed.
Constrain proportions	Retain the proportional dimensions of an image when changing the image size.
Context	The circumstances relevant to something under consideration.
Contrast	The difference in brightness between the darkest and lightest areas of the image or subject.
CPU	Central processing unit - the ‘brains’ of a digital camera or computer.
Crop	Reduce image size to enhance composition or limit information.
Curves	Control for adjusting tonality and color in Photoshop.
Decisive moment	The moment when the arrangement of the moving subject matter in the viewfinder of the camera is composed to the photographer’s satisfaction.
Dedicated flash	A flash unit that is fully linked to the camera’s electronics and uses the camera’s own TTL light meter to calculate correct exposure.
Depth of field	The zone of sharpness variable by aperture, focal length or subject distance.
Diagonal	A slanting straight line that is neither horizontal nor vertical.
Differential focusing	Use of focus to highlight specific subject areas.
Diffused light	Light that is dispersed (spreads out) and is not focused.
Diffuser	Material used to disperse light.
Digital image	A computer-generated photograph composed of pixels (picture elements) rather than film grain.
Diminishing perspective	A sense of depth in a two-dimensional image provided by the reduced size of subjects as they recede into the distance.
Dioptres	Unit of power for close-up lenses.
Dissect	To cut into pieces. The edge of the frame can dissect a familiar subject into an unfamiliar section.
Dpi	Dots per inch. A measurement of print resolution.
Dynamic tension	An image which lacks either balance or harmony and where visual elements cause the eye to move out of the image.
Edit	To either reduce the number of images from a larger collection or to enhance or manipulate a digital image.
Evaluate	Assess the value or quality of a piece of work.
Exposure	Combined effect of volume of light hitting a sensor and its duration.
Exposure compensation	To increase or decrease the exposure from a meter-indicated exposure to obtain an appropriate exposure.
Exposure meter	Device for the measurement of light.
Extreme contrast	A subject brightness range that exceeds the image sensor’s ability to record detail in all tones.
F-numbers	A sequence of numbers given to the relative sizes of aperture opening. F-numbers are standard on all lenses. The largest number corresponds to the smallest aperture and vice versa.
Feather	The action of softening the edge of a digital selection.
Field of view	The area visible through the camera’s viewing system.
Figure and ground	The relationship between subject and background.
Fill	Use of light to increase detail in shadow area.
Fill flash	Flash used at a reduced output to lower subject brightness range.
Filter	Either a treated or colored piece of glass or plastic placed in front of the camera lens or a preset software action that applies an effect to a digital image.
Filter factor	A number used to indicate the effect of the filter’s density on exposure.
Flare	Unwanted light, scattered or reflected within the lens assembly, creating patches of light and degrading image contrast.
Focal length	Distance from the optical centre of the lens to the image plane when the lens is focused on infinity. A long focal length lens (telephoto) will increase the image size of the subject being photographed. A short focal length lens (wide-angle) will decrease the image size of the subject.
Focal plane shutter	A shutter directly in front of the image plane.
Focal point	Point of focus at the image plane or point of interest in the image.
Focusing	The action of creating a sharp image by adjusting either the distance of the lens from the sensor or altering the position of lens elements.
Format	The size of the camera or the orientation/shape of the image.
Frame	The act of composing an image. See ‘Composition’.
Golden section	A classical method of composing subject matter within the frame.
Gray card	Neutral colored card which reflects incident light at a known percentage.
Half-tone	A system of reproducing the continuous tone of a photographic print by a pattern of dots printed by offset litho.
Hard copy	A print.
Hard drive	Memory facility which is capable of retaining information after the computer is switched off.
Hard light	A light source which appears small to the human eye and produces directional light giving well-defined shadows, e.g. direct sunlight or a naked light bulb.
High key	An image where light tones dominate.
Highlight	Area of subject receiving highest exposure value.
Histogram	A graphical representation of a digital image indicating the pixels allocated to each level.
Horizontal	A line that is parallel to the horizon.
Hot shoe	Plug-in socket for on-camera flash.
Incident light reading	A measurement of the intensity of light falling on a subject.
Interpolation	A method of increasing the apparent resolution of an image by adding pixels of an average value to adjacent pixels within the image.
ISO	International Standards Organization. A numerical system for rating the speed or relative light sensitivity of an image sensor.
JPEG (.jpg)	Joint Photographic Experts Group. Image compression file format.
Juxtapose	Placing objects or subjects within a frame to allow comparison.
Key light	The main light casting the most prominent shadows.
Kilobyte	1024 bytes.
Lasso Tool	Selection tool used in digital editing.
Latitude	Ability of the film to record the brightness range of the subject.
Layers	A composite digital image where each element is on a separate layer or level.
LCD	Liquid crystal display.
LED	Light-emitting diode. Used in the viewfinder to inform the photographer of exposure settings.
Lens	An optical device usually made from glass that focuses light rays to form an image on a surface.
Levels	The method of assigning a shade of lightness or brightness to a pixel.
Light meter	A device that measures the intensity of light so that the optimum exposure for the image sensor can be obtained.
Long lens	Lens with a large focal length and thus a reduced field of view.
Low key	An image where dark tones dominate.
Macro	Extreme close-up.
Magic Wand Tool	Selection tool used in digital editing.
Marching ants	A moving broken line indicating a digital selection of pixels.
Marquee Tool	Selection tool used in digital editing.
Matrix metering	A meter reading which averages the exposure from a pattern of segments over the subject area.
Maximum aperture
Megabyte	Largest lens opening.
Megapixels	A unit of measurement for digital files. 1024 kilobytes.
MIE	More than a million pixels.
Minimum aperture	Meter-indicated exposure.
Mode (digital image)	Smallest lens opening.
Multiple exposure	RGB, CMYK, etc. The mode describes the tonal and color range of the captured or scanned image.
Negative	Several exposures made onto the same image frame.
Neutral density filter	An image where the tones are reversed, e.g. dark tones are recorded as light tones and vice versa.
	A filter that reduces the amount of light reaching the image sensor.
Objective
ODR	A factual and non-subjective analysis of information.
Opaque	Output device resolution.
Open up	Not transmitting light. Increasing the lens aperture to let more light reach the image sensor.
Pan	To follow a moving subject.
Perspective	The apparent relationship of distance between visible objects, thereby creating the illusion of depth in a two-dimensional image.
Perspective compression	Flattened perspective created by the use of a telephoto lens and distant viewpoint.
Photoflood	Tungsten studio lamp with a color temperature of approximately 3400K.
Pixel	The smallest square picture element in a digital image.
Polarizing filter	A gray-looking filter used to block polarized light. It can remove or reduce unwanted reflections from some surfaces and can increase the color saturation and darken blue skies.
Portrait lens	A telephoto lens used to capture non-distorted head and shoulder portraits with shallow depth of field.
Portrait mode	A programmed exposure mode that ensures shallow depth of field.
Previsualize	The ability to decide what the photographic image will look like before exposure.
Processor speed	The capability of the computer’s CPU measured in megahertz.
Pushing film	The film speed on the camera’s dial is increased to a higher number for the entire film. This enables the film to be used in low light conditions. The film must be developed for a longer time to compensate for the underexposure.
Push processing	Increasing development to increase contrast or to compensate for underexposure of films that have been rated at a higher speed than recommended.
RAM	Random access memory, the computer’s short-term or working memory.
Reflector	A surface used to reflect light in order to soften harsh shadows.
Refraction	The change in direction of light as it passes through a transparent surface at an angle.
Resample image	Alter the total number of pixels describing a digital image.
Resolution	A measure of the degree of definition, also called sharpness.
RGB	Red, green and blue. The three primary colors used to display images on a color monitor.
Rubber stamp	A tool used for replicating pixels in digital imaging.
Rule of thirds	An imaginary grid that divides the frame into three equal sections vertically and horizontally. The lines and intersections of this grid are used to design an orderly composition.
Saturation (color)	Intensity or richness of color hue.
Scale	A ratio of size.
Selective focus	The technique of isolating a particular subject from others by using a shallow depth of field, also known as differential focus.
Self-timer	A device which delays the action of the shutter release. This can be used for extended exposures when a cable release is unavailable.
Sharp	In focus. Not blurred.
Shutter	A mechanism that controls the accurate duration of the exposure.
Shutter priority	Semi-automatic exposure mode. The photographer selects the shutter speed and the camera sets the aperture.
Silhouette	The outline of a subject seen against a bright background.
Skylight filter	Used to reduce or eliminate the blue haze seen in landscapes. It does not affect overall exposure so it is often used to protect the front lens element from damage.
Sliders	A sliding control in digital editing software used to adjust color, tone, opacity, etc.
SLR camera	Single lens reflex camera. The image in the viewfinder is viewed via a mirror behind the lens which moves out of the way when the shutter release is pressed.
Soft light	This is another way of describing diffused light which comes from a broad light source and creates shadows that are not clearly defined.
Software	A computer program.
Standard lens	A lens that gives a view that is close to normal visual perception.
Steep perspective	Exaggerated diminishing perspective created by a viewpoint in close proximity to the subject with a wide-angle lens.
Stop down	Decreasing the aperture of the lens to reduce the exposure.
Straight photography	Photographic images that have not been manipulated.
Subjective analysis	Personal opinions or views concerning the perceived communication and aesthetic value of an image.
Symmetry	Duplication of information either side of a central line to give an image balance and harmony.
Sync lead	A lead from the camera to the flash unit which synchronizes the firing of the flash and the opening of the shutter.
Sync speed	The fastest shutter speed available, for use with flash, on a camera with a focal plane shutter. If the sync speed of the camera is exceeded when using flash the image will not be fully exposed.
System software	Computer operating program, e.g. Windows or Mac OS.
Telephoto lens	A long focal length lens. Often used to photograph distant subjects which the photographer is unable to get close to. Also used to flatten apparent perspective and decrease depth of field.
Thematic images	A set of images with a unifying idea.
TIFF	Tagged Image File Format. Popular image file format for desktop publishing applications.
Tone	A tint of color or shade of gray.
Transparent	Allowing light to pass through.
TTL meter	Through-the-lens reflective light meter. This is a convenient way to measure the brightness of a scene as the meter is behind the camera lens.
Tungsten light	A common type of electric light such as that produced by household bulbs and photographic lamps. An 80A blue filter may be used to prevent an orange cast.
Unsharp Mask	A filter for increasing apparent sharpness of a digital image.
UV filter	A filter used to absorb ultraviolet radiation. The filter appears colorless and may be left on the lens permanently for protection.
Vantage point	A position in relation to the subject which enables the photographer to compose a good shot.
Vertical	At right angles to the horizontal plane.
Virtual memory	Hard drive memory allocated to function as RAM.
Visualize	To imagine how something will look once it has been completed.
Wide-angle lens	A lens with an angle of view greater than 60o. Used when the photographer is unable to move further away or wishes to move closer to create steep perspective.
X	Synchronization setting for electronic flash.
X-sync (PC socket)	A socket on the camera or flash unit which enables a sync lead to be attached. When this lead is connected the flash will fire in synchronization with the shutter opening.
Zooming	This is a technique where the focal length of a zoom lens is altered during a long exposure. The effect creates movement blur which radiates from the centre of the image.
Zoom lens	A variable focal length lens. Zoom lenses have comparatively smaller maximum apertures than fixed focal length lenses.