21
Coaxial Cable
The type of cable generally used for
TV signals where one conductor is
arranged around the other to provided
a shield, and reduce signal loss.
Composite Video
A video signal that combines the
picture signal, synchronizing pulses
and vertical and horizontal blanking.
Crosstalk
An unwanted signal from different
cable or channel that interferes with
the video signal.
Day/Night (IR sensitive)
Color cameras have a built in infrared
filter to improve color reproduction.
In low light situations in a Day/Night
camera the IR-cut filter in front of the
color sensor is removed restoring the
IR sensitivity of the camera.
DC Iris Lens
See Auto Iris Lens.
Depth of Field
The distance from the nearest to
furthest point which appears in focus.
The smaller the aperture used the
greater the depth of field.
Dynamic Noise Reduction (DNR)
Digital Video processing that measures
the noise in the picture and auto-
matically reduces it appropriately.
Electronic Iris
EI automatically adjusts the camera’s
shutter speed to account for lighting
changes. In some cases eliminating the
need for an auto iris lens. Sometimes
referred to as AES.
F-Number
The standard measure of the Lens
aperture, the iris diameter divided by
the focal length of the lens. The lower
the maximum aperture, the more light
that passes throuth the lens, also
known as a faster lens.
F-Stop
See F-Number.
Focal Length
The distance from the optical center
of the lens to the image of an object
located at an infinite distance from
the lens.
Footcandle
See sensitivity.
Image Size
Lenses are designed to produce an
image to fit the sensor being used.
Sensor sizes are related to the older
tube diameters, and normally quoted
in inches, 1/2", 1/3", 1/4" etc. The
sensor diagonal is dimension used.
Infra-red Illumination
Electromagnetic radiation with longer
wavelength than in the visible spectrum.
Illuminators can be lamps with
appropriate filters, LED’s or IR laser
based. The longer the wavelength the
less sensitive the CCD sensor.
Ref_guide_Camera 10-11-2004 15:46 Pagina 21
