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Tech Tips and Updates

Better video under adverse conditions

Nowadays you can get high quality video from most entry level surveillance cameras. During daytime hours, you’ll get good color rendition. At night, your camera will likely have IR LED’s to provide modest distance viewing albeit in black and white. But many times a low end camera will fall short.

We’ll cut to the chase and say Dahua’s Night Color cameras will give you better video under most adverse conditions. The reasons are many; for one, Night Color Technology provides such good light sensitivity that it doesn’t require IR LED’s for extra illumination. Since it doesn’t have IR LED’s, you eliminate many shortcomings. With IR illumination on, inclement weather like rain or snow can wreak havoc. Rain and snowflakes act as tiny mirrors and reflect light back into the camera sensor and limit visibility.

And if your application requires video analytics, then bad weather at night will create a lot of false alarms because of this effect. With Night Color cameras, you avoid all that.

If you have a lot of insects in the area, using an IR LED camera can have unintended consequences.  IR LED’s can attract insects, and thus spiders like to set up their web where the food is!

Spiders and webs will obscure the view, and you’ll have to clear it away periodically. Even if there are no spiders, moths and other flying insects that are attracted to the LED’s can interfere with viewing. Again, situation avoided with Night Color cameras.

What if you have a covert application, where you want surveillance video but don’t want anyone to know? Since most IR LED’s are 850nm spectrum, they will emit a faint glow visible to the naked eye. Since Night Color doesn’t have IR LED’s, problem averted!

IR LED assisted cameras work great for short to medium distance viewing when it’s dark outside. However at night the background image will suffer because illumination and exposure is optimized for the foreground. In the screenshots below, you can see that the IR illuminated scene has proper illumination of the yard, but you can’t see the cars or houses across the street. With Night color, you can see clearly everything in view of the lens.

Despite the multitude of advantages with Night Color cameras, IR LED assisted cameras still have their advantages. Night Color cameras still require some ambient light, and the minimum is ~1 lux for color. In nighttime outdoor scenes that have no artificial lighting at all, an IR assisted camera is appropriate. To make sure moving objects are properly exposed, look for cameras that have Intelligent IR. Those will adjust exposure as objects approach the camera, so it doesn’t overexpose the object.

In daytime outdoor scenes, or with indoor scenes with interior lighting and an outdoor view, the contrast range may be too wide for regular cameras. Make sure to specify one with True Wide Dynamic range (120dB or higher). This will double-scan the sensor and combine slightly under-exposed and over-exposed images together to keep detail in bright and shadow areas.

In summary, it’s best to take into consideration all the environmental factors of the camera location. Does it rain or snow a lot? Is there very bright and dark areas within view? Do you need to see color 24/7? What is the ambient light level of the outdoor scene you want to view at night? Answering these questions will lead you to the correct camera features and specifications required.