Infrared light is not visible to humans and animals (specifically mammals). For CCTV camera type devices, analog night vision or digital photo traps apply two types of infrared diodes (also laser)-about 850 nm and about 940 nm wavelength. The fact that the light is visible during the operation of such diodes (red) is due to the fact that the LED does not emit in 100% of the ideal wavelength. In the case of LEDs at 850 nm, the shift towards the visible light is much higher than at 940 NM so the observer sees the glow of the LEDs. A man sees a wavelength of 380 – 740 nm. In other mammals it is similar. The experience of hunters suggests that deer can see larger wavelength ranges. This phenomenon is particularly relevant for lower quality LEDs. The 940 nm LEDs are not commonly used because the photoconductive matriculator is less sensitive to this wavelength range. Better image quality We get a case of application 850 nm. The differences are visible especially at long distances. Diodes 940 nm are used in photo traps, where we care to observe up to about 20 meters. The 940 nm LEDs need more energy to illuminate the area.  Power consumption will be greater than at 850 nm.        

Infrared and Game (WG-50)