280 • Additional Reference Information Nano Series GigE Vision Camera
Guidelines for Choosing IR Cut-off Filters
The following graphic, using a color sensor response spectrum, shows the transmission response of
typical filters designed for CMOS sensor cameras. When selecting an IR cut-off filter, choose a near
infrared blocking specification of ~650nm. Filters that block at 700nm or longer wavelengths,
designed for CCD cameras, are not recommended for Genie Nano color cameras.
Necessity for White Balance Calibration with IR Filters
Filter specifications include a range value allowed by the manufacturer for its products. For a Nano
camera with an IR filter the specification states that the filter attenuation is 50% @
650nm +/- 10nm. Therefore the filter’s 50% cutoff can be anywhere between 640 to 660nm and
still be within the filter’s specification.
This small but important variation in filter cutoff frequency will affect the amount of red and green
color reaching the camera sensor. This real world specification variance applies to all filters,
whether included with a Nano model with IR filtering or by filters chosen and installed by clients.
For optimal color representation, the user should perform a white balance calculation/calibration for
cameras that have an IR filter or any other filter installed.
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