Jargon: Explained
AF Sensor
The sensor used to detect and help correct the focus in cameras equipped with an autofocus function.
Angle of View
The width of the area a lens can see; measured in degrees.
Aperture
An opening; this term is used interchangeably with f-stop to denote a camera's diaphragm opening.
Lens Aperture
The physical opening of a lens. The smaller the f/number the more light passes through. Modern lenses use a standard f-stop scale, which is an approximately geometric sequence of numbers that corresponds to the sequence of the powers of the square root of 2: ƒ/1, ƒ/1.4, ƒ/2, ƒ/2.8, ƒ/4, ƒ/5.6, ƒ/8, ƒ/11, ƒ/16, ƒ/22, ƒ/32, ƒ/45, ƒ/64, ƒ/90, ƒ/128, etc.
AVI
Short for Audio Video Interleave; the file format for Microsoft's Video for Windows standard.
Definition
The clarity of detail in an image; dependent upon resolution (number of pixels) and contrast.
Depth of Field
Means of describing the area of a photograph that is in focus.
Dynamic Range
Refers to the gradations of light and dark that a digital camera can capture where details are neither washed out by light nor concealed by shadows.
Exposure
The amount of light that reaches the film; the combination of f-stop and shutter speed, which controls the amount of light that passes through the lens to the film.
File Format
Digital cameras store the data for an image in a file. The format of the file describes how that data is stored. Files in a specific format can only be viewed by software that supports that format. Some common image file formats include TIFF, PICT, and EPS files.
Flash Cards/Memory
Flash memory is a non-volatile type of computer memory. Non-volatile means that the memory will retain its contents indefinitely even if the power is disconnected. Nearly all digital cameras utilise flash memory for storing images because it is robust and the photos taken with the camera will not be lost even if the batteries run out.
Flash memory card
Cameras that have no or only a small amount of internal Flash memory will include a card slot to allow Flash memory cards to be attached for storing images. These cards consist of a chip of Flash memory in a plastic enclosure for easy handling. Flash memory cards add flexibility, as you can carry as many as you need and you can access them from any computer with a card reader - you don't have to connect the camera to the computer to access the images. Some models of photo printer also include card readers meaning you can print off photographs without even having to use a computer at all. Memory cards come in several different formats such as CompactFlash, SD, XD and Memory Stick. Most cameras only support one format, so it is important to make sure your cards are compatible with your camera.
Focal Length
The size of the angle of view of the lens, measured in millimetres (mm). The smaller the number, the wider the lens. Zoom lenses have a range of focal lengths.
Focus
To move the lens or film/image sensor in order to record a sharp image. Auto focus - Camera feature that uses an infrared (IR) beam or sonar to set its focus.
F-Stop
A means of measuring the width of the diaphragm opening, which determines how much light passes through the lens. Smaller numbers in an f-stop correspond to wider lens openings; as the f-stop reading increases in number, the lens opening decreases inversely.
Image Stabilisation
Image stabilisation, IS in short, helps to steady the image projected into the camera to compensate for hand shake. It differs from digital image stabilisation found in most digital video cameras as the later involves manipulation of image pixels to create a stable video image.
ISO
Acronym for International Standardization Organization. This is the numerical expression of light sensitivity. Standard steps are 50, 100, 160, 200, 250, 320, 400, 540, 600, 800, 1000, 1250, 1600 with the lower number being the least sensitive to light conditions.
LCD
Short for Liquid Crystal Display; a small, flat, visual screen that employs liquid crystal technology in order to display images. The screens on the back of most digital cameras are examples of LCD displays
Lens
An optical device that focuses light rays. In cameras, the lens is the device on the front face (or in a tube extending from the front face) that gathers the incoming light and concentrates it so that it can be directed toward the film (in an optical camera) or the imaging device (in a digital camera).
- Wide angle lens
- A lens that has an angle of view greater than that of a standard lens and that is considered of short focal length. This kind of lens is usually employed to include more of a subject within the confines of the image frame.
- Zoom lens
- Lens with variable focal length within a certain range. Fixed focal lens - A lens in which the focus is preset and is not adjustable.
- Fish Eye Lens
- This is an extremely wide-angle lens. A fish-eye lens magnifies the parts of the image near the centre of the image and reduces the parts that are far away from the centre.
- Macro Lens
- Lens that allows close photography with representations larger than 1:1; also called a close-up lens.
Range finder
Device in some cameras used to measure the distance from the camera to the subject and that indicates when the subject is in focus.
Light Meter
A light-sensitive measuring device used to evaluate the amount of light focused on a subject in order to set the proper exposure.
Megapixel
Digital images are made up of a mosaic of small coloured dots, known as pixels. A megapixel simply a group of a million pixels. Megapixels are used as a measure of the quality of a digital image, generally the higher the megapixel count, the better the quality. An image 1280 pixels across by 1024 pixels tall is a 1.3 megapixel image. If the same image is recorded with 2560 pixels across and 2048 pixels up the resulting image would be 5.2 megapixels.
Memory Stick
A family of Flash memory card formats developed by Sony Electronics. Most digital cameras manufactured by Sony use Memory Stick Flash memory for external storage.
Memory Stick is an umbrella term for all of Sony's Flash memory products, members of the family include the original Memory Stick, Memory Stick Pro, Memory Stick Duo and Memory Stick Micro. These formats are not 100% compatible with each other so if you are buying a Memory Stick camera please check that it supports the same type of Memory Stick as any Memory Stick cards you are also intending to purchase or already own.
Resolution
A measure of the proportion of the smallest individually accessible portion of a video image to the overall size of the image. The higher the resolution, the finer the detail that can be discerned.
White Balance
This is the balancing of colour components to create pure white when scanning a white object.
Zoom
A camera with zoom is able to make the subject appear larger when it is photographed, either by optical or digial means
- Optical Zoom
- Optical zoom magnifies the size of an image by adjusting the lens. Unlike digital zoom, optical zoom enlarges the subject without sacrificing resolution. Optical zoom is generally considered to be superior to digital zoom for this reason.
- Digital Zoom
- Uses digital technology to enlarge an image. Digital zoom does not have moving parts. It is the electronic enlarging of the middle of an image. The pixels at the centre portion of the CCD are digitally doubled to make the image appear larger on the display.
