CCTV video security surveillance equipment: camera lenses

There are many technical terms and specifications that you’ll be exposed to when buying surveillance cameras. Here are a few.

Resolution refers to how detailed a picture the camera can see. The measurement to look for is horizontal TV lines (TVL). A normal surveillance camera captures around 350 to 400 TVL, with high resolution cameras getting up to 480 or 500. Upgrading a camera’s resolution can cost as little as $50.

However you need to make sure your entire system is capable of supporting the same resolution. If your DVR records 350 lines and your monitor displays 400, the money you spent to upgrade to a surveillance camera with 500 lines is completely wasted. In the end, the small cost to upgrade your camera may be multiplied by the costs to upgrade other equipment.

Signal to noise ratio (s/n)  indicates how much “signal,” or actual picture information, a surveillance camera transmits, as opposed to “noise,” which comes across as static. A s/n ratio of 40db indicates that the signal is 100 times the noise, which results in an acceptable picture with some fine grain or snow. 30db results in a poor picture, and 60db produces an excellent picture with no static visible. Keep in mind that noise can be introduced by other components in addition to the camera.

Sensitivity to light is measured in lux. A sensitivity of 2 lux means a surveillance camera can see fairly well by the light of a 40W fluorescent bulb; 0.5 lux cameras can make out images outside on a dim night. Your needs will depend on the lighting in the area being filmed, but lux ratings should not be the most important aspect of your surveillance camera decision.