Clear video images in low light scenarios are a must for many security installations. However, with the abundance of options on the market, it can be difficult to know what kind of technology to use. Here, we take the mystery out of low light technology away and give you practical information to help you see more with nighttime surveillance.
When affordability and flexibility are essential, infrared (IR) lighting is a cost-effective option for nighttime surveillance scenes. A camera with built-in IR light emitting diodes (LEDs) will capture an image when there is no light at all, but it's best for short distances. Infrared cameras produce black and white images once the light reaches a certain low level; about 90% of low-light cameras on the market use an IR cut filter (also called "true day / night"). The filter is designed to switch to night mode when the camera detects that insufficient light is available and can no longer provide color images. Users have the added flexibility of changing the threshold at which the camera switches from color to black and white. The standard Dahua ePoE 4MP IR camera (N45CL5Z) is a bestseller, with a 1/3" CMOS lens.
One downside to IR LEDs is that spiders tend to build webs around these cameras - a natural location for them to catch insects that are attracted to the light emitted by the LEDs. This can become a serious problem as cobwebs can obstruct visibility and spiders can trigger false motion detection alerts. Another pain point of IR LEDs is the reflection of rain, which makes it difficult to get a clear video in bad weather.
For an environment where there is a certain amount of lighting, finding a camera that will make video useful won't be a problem. The challenge is when there is no light at all. To meet this challenge, the Dahua portfolio includes three different types of Starlight technology, each with different levels of light sensitivity. Light sensitivity is defined by lux, a unit of illuminance. To give you a comparison, full daylight is 10,000 lux while a full moon is 0.1 lux full moon. A quarter moon emits 0.01 lux and a moonless sky is illuminated by 0.001 lux of starlight.
Basic Starlight, Dahua's most cost-effective Starlight option, offers good low-light performance with 0.008 to 0.009 lux illumination. Enhanced Starlight has - as the name suggests - improved low-light performance, with illumination down to 0.005-0.007 lux.
Starlight + offers the best low light performance of the Starlight product suite: illumination of 0.004 lux or less. This is fantastic for very dark environments, areas that are not well lit without ambient lighting. The 4MP Starlight + ePoE camera (N45DM62), with a 1/1.8" CMOS sensor, provides an image with twice the brightness of the standard 4MP infrared camera mentioned above.
As the name suggests, Night Color cameras deliver color images with superior detail and contrast - at night. These images are suitable for forensic investigations; they will be best in environments that have around 1 lux of ambient lighting, such as street lights. Night color cameras work well at medium and long distances, such as residential locations, parking lots, storefronts, and loading docks. As you can see from the comparison photos, the Dahua ePoE 4MP Night Color Camera (N45EM63) lets you see more, capturing color in dark scenes while other cameras revert to black and white.