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Aperture
The lens
opening formed by the iris diaphragm inside
the lens.
Aperture Priority
AE
Exposure is calculated based on the aperture
value chosen by the photographer. This allows
for depth of field (DOF: Range of focus) control
- large aperture = shallow DOF and a small aperture
= deep DOF.
Brightness
The value of a pixel in an
electronic image, representing its lightness
value from black to white. Usually defined as
brightness levels ranging in value from 0 (black)
to 255 (white).
Contrast
Contrast - A measure of
rate of change of brightness in an image.
Compression
A digital photograph creates
an image file that is huge, a low-resolution
640x480 image has 307,200 pixels. If each pixel
uses 24 bits (3 bytes) for true color, a single
image takes up about a megabyte of storage space.
To make image files smaller almost every digital
camera uses some form of compression. See the
"JPG" entry below.
Exposure
The amount of light that
reaches the image sensor and is controlled by
a combination of the lens aperture and shutter
speed.
Macro
The ability of a lens to
focus very close (less than 8") for taking
pictures of small objects at a 1:1 ratio.
Shutter
The physical device that opens and closes to
let light from the scene strike the image sensor.
Digicams use both electronic and mechanical
shutters.
Pixel
From the english "picture
element". The individual imaging element
of a CCD or the individual output point of a
display device. This is what is meant by the
figures 640x480, 800x600, 1024x768, 1280x960
and etc when dealing with the resolution of
a particular digicam. Higher numbers are always
better!!
Resolution
The number of pixels per
unit length of image. For example, pixels per
inch, pixels per millimeter, or pixels wide.
- The quality of any digital image, whether
printed or displayed on a screen, depends in
part on its resolution—the number of pixels
used to create the image. More and smaller pixels
adds detail and sharpens edges.
- Optical Resolution is
an absolute number that the camera's image
sensor can physically record.
- Interpolated Resolution
adds pixels to the image using complex software
algorithms to determine what color they should
be. It is important to note that interpolation
doesn't add any new information to the image
- it just makes it bigger!
Camera makers often specify the resolution
as: QVGA (320 x 240), VGA (640 x 480), SVGA
(800 x 600), XGA (1024 x 768) or UXGA (1600
x 1200)
Saturation
The degree to which a color
is undiluted by white light. If a color is 100
percent saturated, it contains no white light.
If a color has no saturation, it is a shade
of gray.
Self Timer
Preset time delay (2, 5 or
10 seconds) before the shutter fires. Allows
the photographer to get into the picture without
using a cable release or remote control. It
is also great for taking macro shots as you
don't touch the camera to trip the shutter and
thus eliminates any camera shake.
UV Filter
This is an UltraViolet absorbing
filter that helps overcome the abundance of
blue in outdoor photographs. Not really necessary
in digital photography as the camera's white
balance system adjusts for the color temperature
of the scene. We do use them to protect the
camera's lens from scratching, fingerprints
or dirt.
White
Balance
Refers to adjusting the relative brightness
of the red, green and blue components so that
the brightest object in the image appears white. |
