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Automatic Day/Night Switching

For around-the-clock surveillance or for environments which may restrict the use of visible or artificial light, it may be worth considering a camera which supports automatic day/night switching.

Two images one shot during the day and the other at night using infrared illumination

A true day/night camera will produce high-quality color images during the day and infrared sensitive black and white images in periods of low-light or in complete darkness (with infrared illumination). The way it achieves this is by using an IR cut filter.

Infrared light

Infrared light can be found naturally from many sources including sunlight or artificial light. The human eye cannot register light in the infrared spectrum but the image sensor in a camera can. The problem is that when infrared light is allowed to hit the camera’s image sensor the colors produced by the camera will be distorted from what our eyes normally see and the picture will look unnatural.

The IR cut filter

To get around this problem most cameras contain a special component which filters out infrared light and this gives a high quality image using the colors we are used to. This component is called an IR cut filter. However, having a permanent filter in the camera renders it useless if we want to monitor in the dark using infrared light.

Infrared cut filter

In true day/night cameras the IR cut filter is removable. This means that the camera can produce high-quality images during the day as normal but when the light levels drop the camera automatically removes the filter allowing the camera to see infrared light, enabling the camera to produce high quality images 24 hours a day.

Published on June 13th, 2008 by Greg

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