GLOSSARY OF COMMON TERMS

Aperture – The small, opening inside the lens that can be changed in diameter so as to control the amount of light reaching the camera's sensor. Aperture is expressed in f-stops and the lower the number, the wider the aperture. (e.g. f/2.8 is larger than at f/8). The aperture and shutter speed together control the total amount of light reaching the sensor. A larger aperture passes more light through to the sensor.


Buffer – A memory feature in the camera software that stores digital photos before they are written to the memory card.
Burning – Selective darkening of part of a photo using an image-editing program.


CCD – (Charge Coupled Device)- one of the two main types of image sensors found in digital cameras. When a picture is taken, the CCD is struck by light coming through the camera's lens. Each of the thousands or millions of tiny pixels that make up the CCD converts this light into electrons. The number of electrons, usually described as the pixel's accumulated charge, is measured, and then converted to a digital value. This last step occurs outside the CCD, in a camera component called an analogue-to-digital converter.


CMOS – (Complementary Metal-Oxide Semiconductor)- The other of the two main types of image sensors used in digital cameras. Its basic function is the same as that of a CCD.


CMYK – Cyan, Magenta, Yellow, Black. The four colours in the inksets of many photo-quality printers. Some printers use six ink colours to achieve smoother, more photographic prints. The two additional colours are often lighter shades of cyan and magenta.


CompactFlash™ – A type of digital camera memory card. There are two types of cards, Type I and Type II. They vary only in their thickness, (Type I being slightly thinner). A CompactFlash memory card can contain either flash memory or a miniature hard drive (micro drive). The flash memory type is more prevalent.


Contrast – The difference between the darkest and lightest areas in a photo. The greater the difference, the higher the contrast.


Dodging – Selectively lightening part of a photo with an image-editing program.


DPI – (Dots per inch)- A measurement of the resolution of a digital photo or digital device, including digital cameras and printers. The higher the number, the greater the resolution.


EXIF – (Exchangeable Image File)- The file format used by most digital cameras. For example, when a typical camera is set to record a JPEG, it's actually recording an EXIF file that uses JPEG compression to compress the photo data within the file.


Fill flash – A flash technique used to brighten deep shadow areas, typically outdoors on sunny days. Some digital cameras include a fill flash mode that forces the flash to fire, even in bright light.


FireWire – A type of cabling technology for transferring data to and from digital devices at high speed. Some professional digital cameras and memory card readers connect to the computer over FireWire. FireWire card readers are typically faster than those that connect via USB.


Grayscale – A photo made up of varying tones of black and white. Grayscale is synonymous with black and white.


Highlights – The brightest parts of a photo.


Histogram – A graphic representation of the range of tones from dark to light in a photo. This feature is found in some digital cameras and can be checked with most editing software.


Image browser – A computer software application that allows you to view digital photos.


Image editor – A computer software program that enables you to adjust a photo to improve its appearance. Some programs can be quite advanced and will enable you to carry out quite complex manipulations, far beyond what was achievable in the wet darkroom.


Image resolution - The number of pixels in a digital photo.


ISO speed – The rating of a film's sensitivity to light. Though digital cameras don't use film, they have adopted the same rating system for describing the sensitivity of the camera's imaging sensor. Many cameras allow manual and or automatic of ISO selection. As a rule of thumb, the higher the ISO selected, the more degraded or grainy the picture.


JPEG – (Joint Photographic Experts Group)- A method of compressing image data within a file format. Some quality is lost in achieving JPEG's high compression rates, however, if a high-quality, low-compression JPEG setting is chosen on a digital camera, the loss of quality is not detectable to the eye.


LCD – (Liquid Crystal Display)- A low-power monitor often used on the top and/or rear of a digital camera to display settings or the image itself.


Megabyte (MB) – A data measurement equal to 1024 kilobytes (KB).


Megapixel – One million pixels.


NiMH – (Nickel Metal-Hydride)- The most common type of rechargeable battery that can be recharged many times. NiMH batteries provide sufficient power to run digital cameras and flashes.


Panning – A photography technique in which the camera follows a moving subject which will leave the subject sharp and clear, whilst the background is blurred, giving a sense of motion to the photo.


Pixel – (Picture Element)- Digital photographs are comprised of thousands or millions of them; they are the building blocks of a digital photo.


RAW – The RAW image format is the data as it comes directly off the CCD, with no in-camera processing is performed.


RGB – Red, Green, Blue: the three colours to which the human visual system, digital cameras and many other devices are sensitive.


Saturation – The richness of the colours in a photograph.


Sensitivity – See ISO


Sharpness – The clarity of detail in a photo.


Shutter speed – How long the shutter remains open as the picture is taken. The slower the shutter speed, the longer the exposure time. When the shutter speed is set to 1/60 (60 on adjustment dials or in viewfinder/LCD displays), the shutter will be open for exactly 1/60th of a second. The shutter speed and aperture together control the total amount of light reaching the sensor.


SmartMedia™ — Another type of memory card. This is also a flash-memory based storage medium.


TIFF - (Tag Image File Format)-A widely used bitmapped graphics file format. Because of the compression method, TIFF files are far less susceptible to data loss than JPEGs.


Thumbnail – A small version of a photo often used to display a lot of pictures on a web page. Thumbnails are often linked to a larger version of the image, which is displayed once the thumbnail is clicked.


USB – (Universal Serial Bus)- A computer protocol for transferring data to and from digital devices. Many digital cameras and card readers connect to the USB port on a computer. USB card readers are typically faster than cameras or readers that connect to the serial port, but slower than those that connect via FireWire.