definitions-photo

8/3/2019 definitions-photo

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Elisa Hernandez

APH 2400

Definitions

Aperture:The size of the opening in a lens that governs how much light reaches the sensor

Aperture Priority:

(A/Av) A semi-automatic exposure setting in which the photographer selects the

aperture and the camera determines and sets an appropriate shutter speed to achieve an

accurate exposure

Auto Exposure Lock:

(AEL) A means, usually in the form of a button, of retaining the exposure setting

read from one part of a scene. The shot can then be framed if necessary while ensuring

the previously metered elements of the scene will be accurately exposed.

Autofocus:

A setting in which the cameras lens is able to focus automatically on a specific

part of a scene. All modern cameras have this function.

Bit:

The basic unit of all digital data; bits are either on or off and represented by

the numbers 1 and 0.

Bracketing

A technique in which a variety of exposures, usually three, is made in very quicksuccession of a particular scene in order to ensure correct exposure

Charge Coupled Device:

(CCD) One of the two most common types of sensor used today in digitalcameras and scanners.

Colour Filter Array:

(CFA) A very thin coloured matrix layer that sits above the sensor layer in adigital cameras imaging sensor to enable the sensor to record colour. CFAs feature a

matrix of red, green, and blue squares.

Complementary Metal Oxide Semiconductor:

(CMOS) The second most commonly used sensor in a digital cameras and

scanners.

Compression:

A method of reducing digital file sizes, such as image files, where retaining as

much significant information as possible in order to ensure as high as possible image


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quality. There are two types of compression: lossy compression, such as that used in

JPEG files, discards information that cannot be retrieved- in effect, the higher the

compression the lower the image quality. Lossy compression can result in very small filessizes. In lossless compression, such as that used in TIFF files, information is bundled or

zipped temporarily while the file is stored, and then unzipped when opened. No

information is lost with this compression technique, resulting in high-quality but largeimage files.

Depth of Field:

A term used to describe an images zone of sharpness, or how much of the

image is in focus. The main way to control depth of field is via the lens aperture.

Digital Zoom:

A function offered by many compact cameras. It works by digitally increasing the

size of the pixels being recorded by the sensor, as opposed to an optical zoom, which

magnifies the image through a series of lenses before it reaches the sensor. Increasing the

size of the pixels can result in poor image quality, and for this reason digital zoom shouldbe used only when theres no alternative.

Dots per Inch:

(Dpi) A measurement of the resolution of an output device, such as a printer.

Dynamic Range:

The optical range in a scene between the brightest (highlight) and the darkest

(shadow) areas in which detail is still visible.

Equivalent Focal Length:

(elf) is the optical focal length of the lens once the size of the sensor is taken into

account. The smaller the sensor, the longer the effective focal length of the lens.

Exposure:

It is the amount of light that reaches a cameras sensor or film. It is governed bythe size of the aperture and for how long the shutter remains open (shutter speed).

Exposure Compensation:

It is a way of manually overriding the built-in exposure meter of a camera toprovide more or less light to the sensor or film.

Filter:A glass or plastic attachment that fits in the front of the cameras lens. Filters are

used for a variety of purposes: polarizing filters are used to reduce glare and reflections,

while neutral density filters are used to reduce the light entering the lens.


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F Number:

The measure of the aperture of a lens used for a specific shot. A low f number,

such as f/2, indicates a large aperture, while a high number, such as f/32, indicates a verysmall aperture.

Focal Length:Strictly, the distance in millimeters between a lens optical centre and the focal

point. The focal length is an indication of the magnifying power of the lens.

Histogram:

A visual interpretation in the form of a graph that describes the tonal range of a

given image.

International Standards Organization:

(ISO) Historically, the measurement of the sensitivity of a specific film- the

higher the ISO rating, the more sensitive the film. The rating has been adopted by digital

camera manufactures to reflect how sensitive the sensor is to light for any given shot.

Joint Photographic Experts Group

(JPEG) One of the most commonly used file formats used by digital formats for

storing images.

Kelvin:

The unit of measurement used to describe light temperature.

LCD Screen:

In digital cameras, the small screen usually found at the back of the camera, used

to review (and preview) shots, and to provide information on the cameras settings.

Lens:

The light-capturing and focusing element of all digital cameras. Lenses usually

contain a variety of individual elements that work together to direct and focus the lightfrom the scene onto the sensor.

Macro:

A term used to loosely describe close-up photography or lenses that have theability to greatly magnify the subject.

Manual:

A term used to describe any part of the picture taking process that involves the

photographer to set the aperture and shutter speed based on the cameras, or an external

light meters reading. Manual focus requires the photographer to decide manually on thepoint focus. Taking manual control of the camera greatly increases the creative

possibilities available.


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Metering:

The system by which all cameras assesses exposure. There are various metering

systems from simple spot metering to the more sophisticated evaluative, or matrix,metering.

Mega Pixel:(MP) One million pixels. Megapixels are a measure of resolution most commonly

used to describe the resolution of a cameras sensor or a specific image file.

Noise:

Interference of an electronic signal. In digital photography, noise manifests itself

as unwanted artifacts in the form of clumps of discolored pixels or a grain-like pattern in

the captured image file.

Picture Element:

(Pixel) is the basic unit of all digital images; essentially a tiny square with its own

hue, saturation, and brightness values. Printed or viewed at an appropriate resolution, animages individual pixels should be invisible to the naked eye. If an image is viewed or

printed too large, it may assume a blocky appearance, known as pixelation.

Pixels per Inch:

(Ppi) The resolution of a digital image. The greater the ppi value, the higher the

resolution.

Program:

An exposure option in which the camera automatically sets the shutter andaperture setting depending on the light meter reading. It differs from full Auto in that in

program shift mode; the photographer can select any aperture/shutter exposure

combinations based on the metering reading.

RAW:

A popular file format available in most digital cameras. Raw files are made up ofunprocessed data as captured by the cameras sensor. For this reason, RAW files will

usually need to undergo some form of image editing to obtain the optimum image.

Resolution:

The amount of detail visible in an image determined by the number of pixels. The

term can also be applied to describe the resolving power of a lens.

Red, Green, Blue

(RGB) Primary colors which, when combined, are used to represent all the colors

of the visible spectrum

Rule of Thirds:

A compositional technique used to promote the placement of the subject elements

in key areas of the frame.


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Shutter Delay/Lag:

The time between pressing the shutter release button and the camera taking the

photograph. If sufficiently long, shutter delay can result in fast moving objects movingout of the frame by the time the photograph is taken.

Shutter Priority:(S/Tv) A semi-automatic exposure setting in which the photographer selects the

shutter speed and the camera automatically determines and sets an appropriate aperture

setting to achieve an accurate exposure.

Shutter Speed:

The time taken for the cameras shutter to open and close, thereby determining the

period the sensor is exposed to the light. Some compacts dont have a shutter; the shutterspeed is represented by the sensor being turned on or off.

Stop:

The term used to describe an exposure value. Increasing an exposure by 1 stop,for example, involves doubling the amount of light reaching the sensor, which can be

achieved by either increasing the aperture from f/5.6 to f/8, for example, or reducing theshutter speed from 1/500 sec to 1/250 sec.

Tagged Image File Format:

(TIFF) A popular file format available in most image-editing programs, but nowused less on digital cameras. TIFF files use lossless compression and therefore retain

more image data.

Universal Serial Bus:

(USB) USB sockets and cables are the most common way of connecting printers,

scanners and other devices to a computer.

White Balance:

A system used in both cameras and image-editing software that helps to eradicateunwanted color casts; in other words, white will appear white.

Zone of Sharpness:

See Depth of Field

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