Regular and security cameras typically work best in natural light. Some devices offer enhanced levels of functionality. Their features enable these devices to generate better quality images even in low light conditions. Regular cameras usually find it easy to generate colour images in natural light. To generate clear images, these cameras typically filter out infrared light. Infrared light can distort the colours of the images in comparison to the image as seen by the human eye. To filter out infrared light, these cameras feature infrared-cut filters. As natural light diminishes below a certain level, these cameras usually switch over to and start functioning in the night mode. In this mode, these cameras will remove the infrared-cut filter. As such, the camera will use near-infrared light for delivering high-quality, black and white images. Near-infrared light typically spans from 700 nanometres to 1,000 nanometres. The human eye cannot discern this frequency of light. But, most camera sensors can detect it and utilise it for producing images.
The principle behind which regular cameras function is easy. Our eyes can see objects in reflected light. So, visible light energy hits an object and bounces off it. This enables us to discern the object clearly. Daylight cameras and night vision devices operate on the same principle. The detectors in these cameras receive the light that bounces off an object and turns it into an image. But, these detectors will need to receive sufficient amount of light. Without it, they will not be able to produce an image. This is why many cameras cannot produce high-quality images when used in starlight, moonlight or artificial lights.
However, infrared cameras have the ability to overcome this dependency on light. People refer to these devices as cameras. But, in reality, you could just as well call them sensors. Regular cameras produce images by using visible light. In contrast, infrared cameras do not rely on visible light. Instead, they use heat for producing images. In addition, infrared cameras can even detect variations in the quantum of heat that an object emits. This enables these devices to produce images as shades of grey in black and white images.