SBIG STC-428-OEM CAMERA
USER’S MANUAL
43
Pixel Size
- The smallest resolution element of an electronic camera sensor is
the pixel. Its size is usually specified in microns, such as the STC-428-
OEM’s
4.5 micron pixels. The term is a contraction derived from
“
picture
element”
.
Quantum Efficiency
- Quantum Efficiency (QE) refers to the fractional
number of electrons formed in a sensor pixel for a given number of impinging
photons. Quantum Efficiency is usually plotted as a function of wavelength.
Readout Noise
- Readout noise is a combination of various noise sources
within the sensor.
Resolution and binning
- The resolution of a camera sensor is determined by
its pixel size. Pixel size can be increased by combining or
“
binning
”
more than
one pixel and displaying the combined light received as a single pixel. Doing so
decreases the effective resolution but increases relative sensitivity. It also
shortens the image download time. Maximum absolute resolution is
determined by the size of an individual unbinned pixel and the characteristics
of the optical system you are using.
Saturation
- Saturation refers to
the full well capacity of a sensor’s
pixel as
well as the maximum counts available in the A/D converter. A pixel is said to
be saturated when the number of electrons accumulated in the pixel reaches
its full well capacity. The A/D converter is saturated when the input voltage
exceeds the maximum permissible.
TE Cooler
- A TE cooler is a thermoelectric cooling device used to cool the
camera sensor down to a low operating temperature. Every camera sensor
produces a certain amount of dark current, which accumulates in the pixels
during an exposure. This unwanted dark current is produced by heat, and
high-performance cameras cool their sensors to minimize this effect. The
sensor is mounted to the TE cooler, which in turn, is mounted to a heat sink,
usually the camera head housing. A TE cooler is also often referred to as a
Peltier cooler.
TIFF Image File Format
- The TIFF image file format (which stands for Tagged
Interchange File Format) was developed jointly by Microsoft and Aldus
Corporations to allow easy interchange of graphics images between programs
in areas such as presentation and desktop publishing. MaxIm LT can save and
read image files in this format.
Tri-Color
- Tri-Color refers to color images created using three different colors
mixed into a balanced color image using red, green and blue filters. An object
is imaged three times, once with each color filter. The three images are then
co-added and color balanced using appropriate software, such as MaxIm LT.
Vignetting
- Vignetting is the obstruction of portions of the incoming light
path by parts of an optical system. It usually occurs in the off-axis portions of
the image and is seen as an uneven illumination of the image plane. When
imaging using a vignetted optical system, the corners of the camera sensor will
receive less light. This can be compensated for by using flat-fielding
calibration, but it is usually preferable to physically avoid vignetting if possible.
