The most commonly used infrared wavelength for security camera lighting is 850nm IR, it provides the best performance versus invisibility balance. Although 850nm IR is invisible to the human eye as “light”, it does produce a slight red glow at the LED light source. For this reason, it is not suitable for covert surveillance applications, such as those for Government or Law enforcement. For covert surveillance, 940nm IR light is recommended, because it is completely invisible to humans, even at the light source.
Keep in mind, however, that the 940nm wavelength IR illuminators have 50% less range than 850nm IR illuminators do. Security cameras also vary in IR sensitivity, some cameras will not be as sensitive to 940nm as they are to 850nm. For many long-range security applications, a slight red glow, emitted by the IR lights LEDs, will most likely not be noticed. When considering the advantages in extended coverage range, and camera sensitivity, 850nm wavelength is usually the best choice for most security applications.
For close range, and indoor spaces, when total invisibility is required, 940nm IR illuminators may be a good option.
Example of 850nm(Visible LEDs) Hidden Cameras:
We equipe two pieces of 850nm LEDs smartly into the device as two pieces of time dots to realize the night vision.
Example of 940nm(Invisible LEDs) Spy Cameras:
We equipe three pieces of 940nm LEDs into the device to realize the 5 meters night vision distance.