Aperture:
Variable opening that controls the amount of light passing through
it. Size measured in 'f' stops. Large apertures [wide] such as f2.8
let in lots of light and give shallow Depth of field. Small
apertures [narrow] such as f22 let in much less light but give
greater Depth of field.
Artefact:
A flaw or defect in a digital image
Backlight control:
An exposure compensation introduced when the light is behind the
subject being shot, which would otherwise fool a camera's metering
system into producing a silhouette effect.
Blooming: 'Halos'
and 'streaks' seen around light sources and bright reflections in
digital images.
CCD: A
Charge Coupled Device [chip] converts light into an electrical
charge. One type of digital camera sensor.
CF:
Compactflash.
CMOS: A
Complimentary Metal Oxide Semiconductor [chip] converts light into
an electrical charge. another type of digital camera sensor.
Colour bit depth:
The number of bits used to represent each pixel in an image, the
higher the bit depth, the more colours appear in an image. 1 bit
colour: black and white image with no greys or colour. 24 bit colour
[8 bits per colour - RGB] = 16.7 million colours -'photo realistic'.
Compression:
Squashing data to reduce file sizes, so using less space for
storage, or to enable quicker transfer of files. JPEG, GIF, PNG, are
some formats used.
Contrast:
The range of tones in an image ranging from highlight to shadow.
CYMK:
These
are the four basic colours that all printers use to make all printed
colours from. Known in the commercial printing world as 'four colour
work'. They are Cyan, Yellow, Magenta and Keystone [Black]. Some
inkjet 'photo' printers use additional colours.
Depth of Field:
The area in front of and behind the focus point that is visibly
sharp. Wide-angle lenses and small apertures produce a greater depth
of field. Telephoto lenses and large apertures give shallow depth of
field.
Digital Zoom:
Non-optical zoom mode used in digital cameras. Results in lower
resolution and poorer image quality.
Download:
moving of files from one device to another, as when transferring
images from camera to computer.
DPI: Dots
Per Inch. A measurement of the resolution of a printer or scanner.
DPOF: A
Digital Print Order Format. A new software system which allows
digital camera users to choose images and numbers required, in
camera. Supported by some direct connection printers and high street
outlets.
Driver: A
software program which tells a computer how to operate devices
connected to it, such as a digital camera when downloading images.
EVF:
Electronic Viewfinder. A new addition to digital cameras. A small
LCD screen which is used in place of optical viewfinders, and
usually shows the same information as the LCD on the back the
camera.
Exposure:
The amount of light striking a cameras sensor . Exposure is
determined by a combination of shutter speed [duration] and aperture
[intensity]. Usually decided by the camera. Common exposure modes
available are, Auto, Shutter Priority [Tv -time value], Aperture
Priority [Av - aperture value] and full Manual.
Exposure
Compensation: Changing the
exposure set by the camera by increasing or decreasing it. Usually
set as + or - EV [exposure value].
File: A
single document stored in memory or on disk or hard drive.
File Format:
The way that file information is stored. The most common digital
image file formats are TIFF, JPEG and GIF.
Filter: A
subsidiary lens element [usually of circular glass] that fits onto
the front of lenses, to enhance or change their optical properties,
and therefore the image being taken. Also a function in
computer imaging software that has the same effect.
Firewire:
A
computer interface for connecting external devices. Also known as i-Link
by Sony and IEEE 1394, which is it's formal designation. The default
for Digital Camcorder to computer connection, due the speed of data
transfer, which is bi-directional, unlike USB. With a speed of
400Mbits/sec it has now been joined by a new uprated version,
Firewire 800 - 800Mbits/sec. Although the original is nominally
slower than USB2 - 480Mbits/sec - actual data transfer is still
faster.
Focal Length:
Describes the magnification and field of view of a cameras lens
which is dependent on the size of the imaging sensor used.
Focus: Lens
adjustment to obtain sharply defined image. There are three types.
Fixed focus/Focus free, Autofocus and manual focus.
Format:
The
type a digital camera's sensor conforms to, expressed in ratio terms
not physical size. 4x3[standard TV size]. 3x2[standard 35mm film
ratio]. 4/3rd's standard - refers not only to the ratio but also to
the actual size of the sensor - new digital camera standard
currently being developed by several manufacturers.
Format/Formatting:
A task that must be carried out on all types of computer memory
that stores files, so that the files can be stored and accessed
properly.
Flash Memory:
A type of fast memory chip that retains all its data even when power
is turned off. See memory cards.
GIF: Graphic
Interchange Format.Developed mainly for the exchange of
image files over the web. For use in web pages. Only supports 256
colours [web palette].
Greyscale:
Known
by photographers as a black and white image.
Hue/Saturation:
These controls can be used to alter an image's colours without
affecting contrast or brightness.
Internal Storage:
non-removable camera memory.
Interpolation: Adding
pixels to an image to increase the size it can be printed at.
Also known as Resampling. Does not addextra detail or
information. 'Makes up' the new pixels from adjacent ones. Can lead
to lower image quality.
JPEG:
Universal
file format used to store and exchange image files in a space
efficient way, by using compression. Devised by the Joint
Photographic Experts Group. The main file format used by all digital
cameras to save images taken. The amount of compression used can be
varied, but the larger the compression used, giving small file
sizes, the larger the loss of loss of image quality. This forms the
basis of digital camera image quality settings.
LCD monitor:
Liquid
Crystal Display, a small screen on the back of digital cameras that
allows the user to preview and review the image being taken. Mostly
now of the TFT type. [Thin Film Transistor]
Macro:
A term
used to indicate that a lens can produce a closer than normal image
giving a high magnification. i.e. close-up or macro-mode.
Manual:
The
ability to take control and override the cameras settings, usually
for exposure or focus.
Megapixel:
One
million pixels. Digital cameras are usually defined by how many
megapixels their sensors have. 2mp, 4mp, etc.
Memory Cards:
Removable
chips using 'flash memory' on which a digital camera stores its
image files. Also known as flash cards. Where the name CompactFlash
originated.
MD:
Microdrive.
MM:
Multimedia
MS:
Memorystick
Noise:
Electrical
interference in analogue electrical equipment. In digital cameras
this manifests itself as pixels of the wrong colour in dark areas of
an image, shadows etc. The smaller the size of pixels on a digital
camera's sensor,[ larger sensors are less noisy than smaller ones],
or the higher the ISO setting used, the more prevalent it becomes.
Leads to poorer image quality.
OLED:
Organic
Light Emitting Diode. A new type of viewing screen [display]. Can be
viewed in bright lighting conditions, at greater angles, unlike
LCD's. Beginning to be used in digital cameras.
Optical Viewfinder:
A viewing system that uses no power, but does not always give a
true view due to parallax and focus errors.
Photodiode:
An
individual photosensitive element on a imaging chip [sensor]. The
information it provides becomes one pixel in an image.
Photosite:
Where
individual elements of an imaging chip are located on the chip.
Pixel:
A
small single element of a digital image [PICture ELement].
Power-up:
The act of turning a digital camera on. The time taken to power-up a
camera, from the time of switching it on, until it is ready to take
a picture, is an important measure of the cameras abilities.
PPI:
Pixels per
inch. A measure of the resolution of cameras, scanners and
printers.
Prosumer: A
description of a product that is targeted at, and appeals to, both
professional and consumer buyers. i.e. a camera with professional
features that is sold at consumer prices.
RAM:
Random
Access Memory. Fast computer memory. Expensive. The more RAM a
camera has the quicker tasks can be carried out, and the shorter the
delay between taking shots.
RAW: A new
way of saving images to memory. The image taken is not processed by
the camera and the basic information is saved 'raw'. Cannot be viewed on a
computer until the image has been processed by 'raw converter'
software. Allows the user to process images as they require them,
but can be labour intensive and time consuming. Only found on
certain cameras, mainly for professional use. No set file standard.
Software provided by the camera maker.
Recovery Time:
The
time taken by a digital camera to process and write an image file to
memory, before another shot can be taken.
Refresh rate:
How
many times a second a screen, LCD or TV, is updated. Under 15 looks
decidedly 'jerky'
Removable media:
Memory cards. Compact Flash and Smartmedia were the original
types.
Resampling:
Changing the number of pixels in an image. see interpolation. Used
by many digital cameras to produce image files that are larger or
smaller than the number of pixels on their sensors. i.e.
'upsampling' to produce a 12mp file from a 6mp sensor.
'downsampling' to produce a 3mp file from a 6mp sensor.
Resolution:
A
measurement used to indicate the amount of information in an image.
Printer resolution measured in DPI [dots per inch]. Digital camera
resolution is in pixels, usually defined by the total number of
pixels captured, 3mp,6mp etc, or by the size, 1600x1200 [2mp],
2048x1536 [3mp], 3008x2008[6mp].
RGB:
Digital
cameras, TV's, computer monitors, camcorders etc all use a mixture
of Red, Blue and Green light to represent all the colours in an
image.
ROM:
Read-only memory. information stored in a memory that can be read
from but not written to [altered]. CD-Rom is a good
example.
Saturation:
The
amount of grey in a colour. Less grey in an image, colours are
richer in hue [deeper]. More grey, colours are weak [lighter].
SD:
Secure
digital
Shutter:
A
blind which opens to let in light. In a digital camera this controls
when the light passing through the lens hits the imaging sensor.
Shutter speed:
The
amount of time a digital cameras sensor is exposed to light. Short
[quick] shutter speeds, measured in hundreds or thousands of a
second are possible in bright light, can 'freeze' motion, and
prevent 'camera shake'. Long [slow] shutter speeds are measured in
tenths or even whole seconds, and are used in poor light or
night-time shots, where a tripod [camera support] is needed to
prevent 'camera shake' and a blurry shot.
Shutter lag:
The
delay between pressing the shutter button and the shot being taken.
A problem with some digital cameras where there is a marked delay,
leading to missed shots.
SM:
Smartmedia.
Start
Up Time: The time it
takes from when a digital camera is switched on to when it is
ready to take a picture. Some have very slow start up times,
many seconds. The latest DSLR's can shoot almost instantly.
Subject/Scene modes:
Specific exposure modes available in many digital cameras, which
are tailored to suit certain situations. Portrait, landscape, macro
etc.
Telephoto Lens:
A lens of longer focal length which brings subjects closer so
enables a shot to be taken from further away.
TFT:
Thin
Film Transistor. A new version of LCD screen which gives better,
brighter colours. Used in most digital cameras.
TIFF:
Tagged
image file format. The standard un-compressed file format. Using it
results in high quality images, no artefacts resulting from
compression, but produces large image files sizes.
Twain:
Computer
protocol for exchanging information between devices such as camera
and computer.
USB:
Universal
Serial Bus. A computer
interface for connecting devices such as camera and computer.
Designed to replace serial and parallel port connections. Data
transfer rate is slow at only 12Mbits/sec. Plug and Play design.
Devices can be connected and disconnected without re-starting the
computer.
USB2:
New
high speed version of USB, allows quicker transfer of data.
480Mbits/sec data rate.
Video output:
Many
digital cameras can display the images on their memory cards on a TV
or record them to video [VHS].
White balance:
Enables
digital cameras to take images without a 'colour cast', caused
either by the level of brightness or artificial lighting. Usually
automatic, but in many cameras can be over-ridden and set manually
or by using 'pre-sets'.
Wide angle Lens:
A lens of a short focal length which makes subjects seem far
away, allowing more of a subject or a scene to be fitted into a
photo at close distance.
Zoom Lens:
A
lens that incorporates a range of focal lengths. A 'standard' zoom
range will often go from wide angle to telephoto.
