Is infrared light visible?
Infrared light is invisible to human eyes. The visible light spectrum to human wavelength ranging from 380 to 740nm, while the invisible infrared wavelength is 740nm or above.
Why can we see infrared radiator?
Wavelengths under 940nm is “semi-covert” infrared”, close to red light. Human eyes can still see the radiator (LED) indistinctly.
Wavelengths that go beyond 940nm is “covert infrared” and in invisible to human eyes. Due to the poorer performance of covert infrared on CCD cameras, semi-covert infrared 850nm has been the mainstream for CCTV.
Can we see everything with infrared?
NO. Infrared is emitted by all objects such as humans, animals, and grass. CCD’s picturing an image depends on the reflection of objects. As a result, the higher reflectance of an object is the easier the scene can be captured. The following table shows the IR reflectance of different objects:
| INDOOR |
IR REFLECTANCE |
| Object in white color |
90% |
| Glass, Walls |
70% |
| People, Animals |
50% |
| Concrete Floor |
40% |
| OUTDOOR |
| Snow |
85% |
| Object in white color |
60% |
| Red Brick |
35% |
| Trees, Grass, Fields |
20% |
| People, Animals |
20~35% |
| Tar, Bitumen |
5% |
| Water, Oceans, Rivers |
0% |
Do more LEDs mean further light projecting?
NO! The main factor in projecting distance is the condensing intensity of the radiator. Therefore, to increase the projecting distance you must improve the condensing intensity of each LED instead of increasing the number of LEDs.
Simply adding the number of LEDs can only increase the radiation area within a short distance, instead of extending the light projecting distance. More LEDs will result in more heat. Once the heat is unable to dissipate rapidly, it will cause low illumination and shorten the life of the LEDs.
How do I choose a CCTV camera lens?
The lens is an optical device for focusing a desired scene onto the imaging device in a CCTV camera. Selecting an appropriate lens is very critical because it directly affects the size, shape, and sharpness of the image to be displayed on the image.
Camera lenses can be divided into two basic types: fixed focal and vari-focal. A fixed focal lens has a constant focal length, while a vari-focal lens can change its focal length
