Ordinary CCD sensors in digital cameras have primitive sensitivity to the radiation up to about 1.1 ƒÊm.
A cut-off filter is put in front of a CCD to shield the NIR light, while passing visible light, so as to accommodate with the color sensitivity of human eyes.
In the night-shot mode, the cut-off filter against NIR band is removed, so as to increase the sensitivity under dark situation, with the sacrifice of the color balance.
In the night shot mode equipped with an IR filter to cut-off the visible band with the boundary around 840 nm as shown in the above figure, one can get NIR images of 0.84-1.1 ƒÊm.
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