Firstly, What is Infrared?

Infrared radiation or IR is a type of radiant energy that can be felt as heat however is invisible to the human eye. All objects emit a certain level of radiation however the sun is one of the more obvious sources of (IR) infrared radiation as we can feel the heat emitted from the sun, however, we cannot see the wavelengths of heat energy as they touch our skin. IR light can be found on the electromagnetic spectrum between visible and microwaves. We can see objects using infrared by capturing footage with special cameras that can detect differences in temperature and assign different brightnesses/false colours to them based on their temperature distribution. Cameras such as the Stortech D057 are able to provide this functionality.

What are the Two Most Common Wavelengths?

When choosing CCTV there are two more common IR wavelengths measured in nanometers. With visible light ranging from 390nm to 700nm the infrared radiation used in CCTV security tends to be either 850nm or 940nm. These light ranges allow us to see images that would otherwise fall outside of our visible range and will vastly improve night vision capabilities for cameras when capturing video or images. 

940nm vs 850nm

What is the Difference Between 850nm and 940nm?

850nm and 940nm are very similar, however, come with a few subtle differences which may affect your decision depending on what you're trying to capture. The majority of more accessible CCTV systems will use 850nm (nanometers). This infrared light is completely invisible to the human eye however will produce a red glow when looking directly into the camera lens. This is important to note as this red glow can be confused with other signals such as brake lights on a vehicle or stop signals during covert operations. 

940nm also known as 'covert IR' will not produce this red glow making it the ideal camera to use during covert operations and in the transport industry. The main disadvantage of 940nm over 850nm is that they are 30% less effective when illuminating over distance. When capturing footage using a separate illuminator you will need to ensure both the camera and illuminator are compatible. The illuminator will need to produce the same wavelength that the camera is sensitive to e.g. both will need to state 850 nanometer IR. 

"Most Security Cameras with built-in IR LED’s, use an IR Cut Filter in order to maximize different lighting conditions during the day or night. During the daytime, the filter is on in order to filter out Infrared Light, that way, color images are not distorted by IR Light. During the nighttime, the IR cut filter is automatically switched off to allow infrared light to enter the camera. The camera switches to IR mode (Black and White) which is more sensitive to Infrared light." (https://ellipsesecurity.com/2018/05/850nm-vs-940nm-ir-illuminator/)

850nm E-Marked Dome Camera

  1. D057-650 IR - 3.6mm lens - Stortech
    £132.00 £110.00
    • 3.6mm Lens
    • 850nm IR
    • 650TVL Resolution
    • CCD Sensor
    • 360 Coverage
    • IP67 Weatherproofing
    • Flush Mounted
    • Polycarbonate Housing
    • 0.00 Lux Sensitivity

940nm E-Marked Dome Camera

  1. D057-650 IR - 3.6mm lens - Stortech
    £132.00 £110.00
    • 3.6mm Lens
    • 940nm IR
    • 650TVL Resolution
    • CCD Sensor
    • 360 Coverage
    • IP67 Weatherproofing
    • Flush Mounted
    • Polycarbonate Housing
    • 0.00 Lux Sensitivity