Infrared night vision uses reflected near-infrared light to record a scene when visible light is low. A compatible camera can produce black-and-white video in complete visible darkness when its built-in LEDs or a separate IR illuminator light the area. It is different from thermal imaging.
What is Infrared Night Vision on a Security Camera?
Infrared and visible light are different wavelengths of the electromagnetic spectrum. Visible light is what we can see. Infrared radiation acts similarly but is invisible to the eye. Cameras can use infrared to capture images in the absence of visible light.
Key Takeaways: Infrared Night Vision in Security Cameras
- Infrared Night Vision: Allows cameras to capture clear images in pitch-black environments using IR radiation, invisible to the naked eye but detectable by sensors.
- IR LEDs and Illuminators: Supply near-infrared light for the camera to see. Some LEDs show a faint red glow; they do not make an installation invisible.
- IR Cut-Off Filter: Prevents unwanted IR radiation during the day for clear images. At night, it moves away to allow IR mode.
- Dynamic/Smart Infrared: Adjusts IR intensity automatically to prevent over-illumination and ensure clear footage, particularly useful for varying distances and lighting conditions.
- Comparison with Full-Color Night Vision: Full-color relies on visible light and provides natural images, but requires some ambient lighting unlike infrared which can operate in complete darkness.
Near-infrared night vision can be discreet, but it does not guarantee an invisible camera. Some IR LEDs show a faint red glow, and the housing may still be visible.
IR LEDs Illuminators Explained
For security cameras to capture night vision footage, they need to light up a scene with IR (Infrared) rays and detect the reflected IR rays like a normal camera. To “illuminate” a scene for night vision, the cameras need LEDs or bulbs that emit IR radiation.
A day/night camera can use available near-infrared light, but a completely dark scene needs an illuminator. Many models automatically move the IR-cut filter out of the optical path and enable built-in IR when the light falls; the available modes depend on the camera.
Many surveillance illuminators use 850 nm LEDs, which can show a faint red glow. A 940 nm source is less conspicuous, but the camera must be sensitive to that wavelength. Check compatibility before adding an external illuminator.
IR Cut-Off Filter Explained
Many security camera image sensors respond to visible and near-infrared light. In daytime color mode, unwanted IR can alter colors, which is why a day/night camera uses an IR-cut filter.
To prevent this, the cameras have a filter that blocks IR radiation. During the day, when there’s enough visible light, the filter covers the sensor, blocking IR radiation. At night, with almost no visible light, the filter moves away, and the camera switches to night vision IR mode.
IR Distance and Lux Explained
IR distance describes the illuminator’s stated reach. Lux measures visible illuminance; it does not measure the strength of an infrared beam. Treat these as different specifications.
Choose an IR beam that covers the required view and distance. A longer advertised range is not automatically better: nearby walls or close subjects can reflect too much light back, while the edges remain dark.
A minimum-illumination figure describes the maker’s chosen visible-light conditions for an acceptable image. Compare shutter, aperture and other test settings where given. It is not a promise of a noise-free moving subject, and figures from different manufacturers may use different criteria.
What is Dynamic/Smart Infrared?
The use of infrared radiation to capture images is a valuable feature for security cameras. However, while it can “see” in complete darkness, excessive IR radiation can also ruin the footage.
Manufacturers have created the Dynamic/Smart Infrared feature to prevent IR illuminators from “over-illuminating” a scene. This feature automatically adjusts IR intensity, ensuring the image is clear and interpretable.
Smart IR behavior varies by model. Compare it on and off with a person both near the camera and at the required distance; look for washed-out faces as well as dark areas. An automatic setting cannot remove a physical obstruction.
Tips to improve your security camera’s infrared night vision
Visible lighting can provide color detail where the camera and scene support it. Compare the saved footage with IR mode before deciding: a bright static image can still blur a moving face if the exposure is too long.
If you want to keep things dark to surprise intruders, use the IR feature. Enhance the area with external infrared sources. Ensure there’s no over-illumination and that these devices have enough power.
Besides that, several other tips and tricks apply to both visible light and IR:
- Cleaning the camera lens regularly
- Make sure your camera switch to night mode
- Choosing the right camera for the location (make sure every point of interest is in focus and not too far. You can read up about DORI here)
- Compare Dynamic/Smart IR settings using a recorded walk test. Its usefulness depends on the scene and the camera, not simply whether the area is outdoors.
- Installing the cameras away from light sources. (Don’t want the footage to get over-exposed.)
Besides that, choose a camera with specs like megapixels, resolution, and focal length that fit the area you’re covering.
Difference between Infrared and Full-Color Night Vision
Night vision is a broad description. Near-infrared and full-color low-light cameras use different parts of the light spectrum; thermal cameras form images from emitted heat and are a different technology.
Color night vision replicates a well-lit, natural image using minimal visible light. Full-Color night vision doesn’t rely on IR radiation.
Full-color footage needs visible light from the scene or a lamp. Some cameras can switch to IR monochrome when it is too dark, while others have no IR illuminator. Check the actual model rather than assuming an automatic fallback.
Why IR Glare Can Look Like Fog
Built-in IR can bounce from a nearby wall, eave, window or dirty dome back into the lens. Clean the cover as the manufacturer directs and move reflective objects out of the IR beam. The beam may reach beyond what is visible in the video frame.
For a camera behind a window, turning off its built-in IR may remove the reflection, but the scene still needs suitable illumination outside. PIR motion detection is a separate issue: a clear live picture through glass does not prove that motion-triggered recording will work.
Conclusion
IR can provide useful monochrome footage without visible lighting. Verify a moving subject at the distance you need; illuminator range alone does not guarantee a recognizable face or a readable license plate. Keep visible lighting where color information is needed.