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InfraRed Sensitive
Colour Cameras
Ordinary Colour CCTV Cameras are
relatively insensitive to Infrared because they have an IR CUT
Filter between the Lens and Image Sensor, this filter blocks
Infrared radiation with a wavelength greater than ~ 700 nm that
would otherwise adversely affect White Balance, Colour Rendition and
Image Sharpness.
Colour CCTV Cameras that are sensitive to
Infrared either do not have an IR CUT Filter or utilise a special
NOTCH IR CUT Filter that excludes the wavelengths most harmful to
colour quality (720 ~ 830 nm) from reaching the Image Sensor.
A Colour CCTV Camera that does not have an
IR CUT Filter usually has poor
colour rendition characterised by a
Pink-Red
'tint' when the illumination is InfraRed rich,
use of a 'Notch' Filter helps however White Balance,
Colour Rendition and Image Sharpness are compromised
for Infrared sensitivity.
Infrared rich
light sources include Daylight and most Filament type lamps
including common Spot lamps, Tungsten lamps, Halogen lamps, etc.
The majority of Light emitted from 'Cold'
type sources such as Fluorescent, Mercury Vapour, Sodium Vapour,
etc., is visible, these sources contain little Infrared energy.
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Air