Angle of view. The amount of a scene that can be recorded by
a particular lens; determined by the focal length of the lens.
Adapter. Used to insert a smaller storage
device into a larger slot in a computer or other device.
Additive color system. See RGB.
Aperture, maximum. The largest size of the
hole though which light enters the camera.
Aperture. The lens opening formed by the
iris diaphragm inside the lens. The size of the hole can be made larger or
smaller by the autofocus system or a manual control.
Aspect ratio. The ratio between the width
and height of an image or image sensor.
ATA. A standard for storage devices that
lets them be treated as if they were hard drives on the system. Any ATA
compatible media can be read by any ATA device.
Attachment. A file such as a photography
sent along with an e-mail message so it can be viewed or saved at the
recipient’s end.
Automatic exposure. A mode of camera
operation in which the camera automatically adjusts the aperture, shutter
speed, or both for proper exposure.
Automatic flash. An electronic flash unit
with a light-sensitive cell that determines the length of the flash for
proper exposure by measuring the light reflected back from the
subject.
Back-lit. The subject is illuminated from
behind and will be underexposed unless you use fill flash or exposure
compensation.
Bayer pattern. A pattern of red, green, and
blue filters on the image sensor’s photosites. There are twice as many
green filters as the other colors because the human eye is more sensitive
to green and therefore green color accuracy is more important.
Bit-mapped. Images formed from pixels with
each pixel a shade of gray or color. Using 24-bit color, each pixel can be
set to any one of 16 million colors.
Burst mode. The ability of a camera to take
one picture after another as long as you hold down the shutter release
button.
Card. The sealed package containing storage
chips or other devices with electrical connectors that make contact when
inserted into a card slot on a camera, printer, computer, or other
device..
CCD raw format. The uninterpolated data
collected directly from the image sensor before processing.
CCD. See Charge-coupled device.
Charge-coupled device (CCD). An image sensor
that reads the charges built up on the sensor’s photosites a row at a
time.
CMOS image sensor. An image sensor created
using CMOS technology.
CMOS. See CMOS image sensor.
Color balance. The overall accuracy with
which the colors in a photograph match or are capable of matching those in
the original scene.
Color depth. The number of bits assigned to
each pixel in the image and the number of colors that can be created from
those bits. True Color uses 24 bits per pixel to render 16 million
colors.
CompactFlash. A popular form of flash
storage for digital cameras.
Compression,
lossless. A file compression scheme that makes a file
smaller without degrading the image.
Compression,
lossy. A file compression scheme that reduces the size
of a file but degrades it in the process so it can’t be restored to its
original quality.
Compression. The process of reducing the
size of a file.
Depth of field. The distance between the
nearest and farthest points that appear in acceptably sharp focus in a
photograph. Depth of field varies with lens aperture, focal length, and
camera-to-subject distance.
Docking station. A small base connected to
the computer by a cable. You insert the camera or other device into the
docking station to transfer images.
Download. Sending a file from another device
to your computer.
Exposure. 1. The act of allowing light to
strike a light-sensitive surface. 2. The amount of light reaching the
image sensor, controlled by the combination of aperture and shutter
speed.
Exposure compensation. The ability to adjust
exposure by one or two stops to lighten or darken the image.
Exposure/focus
lock. The ability to point at one part of the scene
and hold the shutter button half-way down to lock in exposure and focus
settings when you point the camera elsewhere to compose the scene.
Firewire. Apple’s name for IEEE
1394.
Flash card reader. An accessory that
attaches to your computer by cable. You insert a flash memory card into
the reader to transfer files.
Flash memory card. A card containing chips
that store images.
Flash memory. A form of memory using chips
instead of magnetic media. The data in the device isn’t lost when the
power is turned off.
Flash, fill. Flash used to fill shadows even
when there is enough light to otherwise take the photograph.
Flash, ring. A special circular flash that
fits over a lens to take close-up pictures
Flash, slave. A flash that fires when it
senses the light from another flash unit.
FlashPix. An image format that contains a
number of resolutions, each of which is broken into tiles that can be
edited and displayed independently.
Floppy drive. A storage device on almost all
computers that accepts 3 � or 5 �-inch floppy disks.
Focal length. The distance from the optical
center of the lens to the image sensor when the lens is focused on
infinity. The focal length is usually expressed in millimeters (mm) and
determines the angle of view (how much of the scene can be included in the
picture) and the size of objects in the image. The longer the focal
length, the narrower the angle of view and the more that objects are
magnified.
Focus lock. See Exposure/focus
lock.
Focus. The process of bringing one plane of
the scene into sharp focus on the image sensor.
Frame grabber. A device that lets you
capture individual frames out of a video camera or off a video tape.
Frame Rate. The number of pictures that can
be taken in a given period of time.
f-stop. A numerical designation (f/2, f 2.8,
etc.) indicating the size of the aperture (lens opening).
GIF. An image file format designed for
display of line art on the Web.
Gray market. Importing camera equipment
outside of the normal manufacturer’s distribution channels to take
advantage of lower prices elsewhere in the world.
Gray scale. A series of 256 tones raging
from pure white to pure black.
Guide number. A rating of a flash’s
power.
Hot shoe. A clip on the top of the camera
that attaches a flash unit and provides an electrical link to synchronize
the flash with the camera shutter.
IEEE 1394. A new
port on the computer capable of transferring large amounts of data.
Currently the fastest available port.
i.Link. Sony’s name for IEEE
1394.
Image sensor. A solid-state device
containing a photosite for each pixel in the image. Each photosite records
the brightness of the light that strikes it during an exposure.
Infrared. See IrDA.
International Organization for
Standardization. See ISO.
Interpolation. In an image interpolation
adds extra pixels. It’s done with some zoom lenses.
Inverse square law. The physical law that
causes light from a flash to fall off in such a way that as flash to
subject distance doubles, the light falls off by a factor of four.
IrDA. An agreed upon
standard that allows data to be transferred between devices using infrared
light instead of cables..
ISO. A number rating
indicating the relative sensitivity to light of an image sensor or
photographic film. Faster film (higher ISO) is more sensitive to light and
requires less exposure than does slower film.
JPEG. A very popular digital camera file
format that uses lossy compression to reduce file sizes. Developed by the
Joint Photographic Experts Group.
Landscape mode. Holding the camera in its
normal orientation to hake a horizontally oriented photograph.
Lempel-Ziv-Welch. See LZW.
LiOn. Lithium ion battery.
Long-focal-length
lens (telephoto lens). A lens that provides a narrow
angle of view of a scene, including less of a scene than a lens of normal
focal length and therefore magnifying objects in the image.
Lossless. See Compression,
lossless.
Lossy. See Compression,
lossy.
LZW. A compression scheme
used to reduce the size of image files.
Macro mode. A lens mode that allows you to
get very close to objects so they appear greatly enlarged in the
picture.
Matrix Metering. An exposure system that
breaks the scene up into a grid and evaluates each section to determine
the exposure.
Megapixel. An image or image sensor with
over one million pixels.
Memory stick. A flash memory storage device
developed by Sony.
Moore’s Law. Gordon Moore’s law that
predicted that the number of transistors on a chip would double every 18
months.
Motion Pictures Expert Group. See MPEG.
MPEG. A digital video
format developed by the Motion Pictures Expert Group.
Multi-megapixel. An image or image sensor
with over two million pixels.
Multiple exposure mode. A mode that lets you
superimpose one image on top of another.
Multiple exposure. An image made up of two
or more images superimposed in the camera.
NiCad. Nickel cadmium battery.
NiMH. Nickel metal hydride battery.
Ecologically safe and very efficient.
Noise. Pixels on the image sensor that
misread the light.
Normal-focal-length lens. A lens that
provides about the same angle of view of a scene as the human eye and that
does not seem to magnify or diminish the size of objects in the image
unduly.
NTSC. A US video out standard to display
images on a TV screen.
Open up. To increase the size of the lens
aperture. The opposite of stop down.
Operating system. The program that controls
the camera’s or computer’s hardware.
Optical viewfinder. See Viewfinder.
Orientation sensor. A sensor that knows when
you turn the camera to take a vertical shot and rotates the picture so it
won’t be displayed on it’s side when you view it.
Overexposure. Exposing the image sensor to
more light than is needed to render the scene as the eye sees it. Results
in a too light photograph.
PAL. A European video out standard to
display images on a TV screen.
Panorama. A photograph with much wider
horizontal coverage that a normal photograph, up to 360-degrees and
more.
Panoramic mode. A digital camera mode that
uses just the center band on the image sensor to capture an image that is
much wider than it is tall.
Parallax. An effect seen in close-up
photography when the viewfinder is offset by some distance from the lens.
The scene through the viewfinder is offset from the scene through the
lens.
Parallel port. A port on the computer that
is faster than a serial port but slower than SCSI, USB, or IEEE 1394
ports. Often used by printers and flash card readers.
PC card. A card, in
the case of cameras usually a storage device, that plugs into a slot in a
notebook or hand-held computer. Originally called PCMCIA cards.
PCMCIA card. See PC
Card.
Photosite. A small area on the surface of an
image sensor that captures the brightness for a single pixel in the image.
There is one photosite for every pixel in the image.
Picture elements. See Pixels.
Pixelization. An effect seen when you
enlarge a digital image too much and the pixels become obvious.
Pixels. The small picture
elements that make up a digital photograph.
Port. An electrical connection on the
computer into which a cable can be plugged so the computer can communicate
with another device such as a printer or modem.
Portrait mode. Turning the camera to take a
vertically oriented photograph.
Preview screen. A small LCD display screen
on the back of the camera used to compose or look at photographs.
Prosumer. A very serious photographer who
can be either an amateur or professional.
Rangefinder. A camera design that has a
viewfinder separate from the lens.
Read out register. The part of a CCD image
sensor that reads the charges built up during an exposure.
Recycle time. The time it takes to process
and store a captured image.
Red-eye reduction mode. A mode that fires a
preliminary flash to close the iris of the eye before firing the main
flash to take the picture.
Red-eye. An effect that causes peoples eyes
to look red in flash exposures.
Refresh rate. The time it takes the camera
to capture the image after you press the shutter release.
Removable media. Storage media that can be
removed from the camera.
Resolution, interpolated. A process that
enlarges an image by adding extra pixels without actually capturing light
from those pixels in the initial exposure.
Resolution, optical. The true resolution of
an image based on the number of photosites on the surface of the image
sensor.
Resolution. An indication of the sharpness
of images on a printout or the display screen. It is based on the number
and density of the pixels used. The more pixels used in an image, the more
detail can be seen and the higher the image’s resolution.
RGB. The color system used
in most digital cameras where red, green, and blue light is captured
separately and then combined to create a full color image.
Scanner. An input device that uses light to
read printed information including text, graphics, and bar codes, and
transfers it into the computer in a digital format.
SCSI port. A port that’s faster than the
serial and parallel ports but slower and harder to configure than the
newer USB port. Also know as the Small Computer System Interface.
Serial port. A very slow port on the
computer used mainly by modems. Many digital cameras come equipped with
cable to download images through this port but it’s slow! Both parallel
and USB ports are faster connections.
Short-focal-length lens (wide angle). A lens
that provides a wide angle of view of a scene, including more of the
subject area than does a lens of normal focal length.
Shutter Speed. The length of time the
shutter is open and light strikes the image sensor.
Shutter. The device in the camera that opens
and closes to let light from the scene strike the image sensor and expose
the image.
Shutter-priority mode. An automatic exposure
system in with you set the shutter speed and the camera selects the
aperture (f-stop) for correct exposure.
Single-lens reflex. See SLR.
SLR. A type of camera with
one lens which is used both for viewing and taking the picture.
SmartMedia. A popular form of flash memory
card.
Spot Metering. Autoexposure is based on a
meter reading of a small circle in the center of the viewfinder.
Stop 1. An aperture setting that indicates
the size of the lens opening. 2. A change in exposure by a factor of two.
Changing the aperture from one setting to the next doubles or halves the
amount of light reaching the image sensor. Changing the shutter speed from
one setting to the next does the same thing. Either changes the exposure
one stop.
Stop down. To decrease the size of the lens
aperture. The opposite of open up.
Tagged Image File Format. See TIFF.
Telephoto lens. See Long-focal-length
lens.
Thru-the-lens. See TTL.
TIFF. A popular lossless
image format used in digital photography.
Time-lapse photography. Taking a series of
pictures at preset intervals to show such things as flower blossoms
opening.
TTL. A camera design that
let’s you compose an image while looking at the scene through the lens
that will take the picture. Also called thru-the-lens.
Unbundling. When a dealer removes normally
included items from a camera package and then sells them to you
separately.
Underexposure. Exposing the film to less
light than is needed to render the scene as the eye sees it. Results in a
too dark photograph.
Upload. Sending a file from your computer to
another device.
URL (Uniform Resource Locator). The address
of a Web site.
USB port. A high-speed port that lets you
daisy-chain devices (connect one device to another).
VGA. A resolution of 640 x 480.
Video card. A card the fits into a
computer’s expansion slot so you can edit digital video.
Viewfinder. A
separate window on the camera through which you look to compose
images.
White balance. An automatic or manual
control that adjusts the brightest part of the scene so it looks
white.
Wide-angle lens. See Short-focal-length
lens.
Zoom lens. A lens that lets you change focal
lengths on the fly.
| The Glossary of Digital Photography Terms
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