May 10, 2013

What You Should Know About Surveillance Cameras

surveillance cameraVideo surveillance has been around since the 1940s and technology has played a major role in making these systems affordable and reliable. Video surveillance isn’t like a computer where it is one size fits all. A properly installed surveillance system requires an understanding on how video cameras function in all lighting and environmental conditions.

Surveillance systems are becoming more affordable and are everywhere today from banks and warehouses to homes and car washes.

The installer must also understand common installation problems and how to prevent them from ever occurring. Also, the installer must know what camera options are available and how they fit together for the application it is intended. One camera may work fine in one setting but not another. Some options are:

  • Auto iris lenses
  • Fixed iris lenses
  • Variable and fixed focus lenses
  • PTZ cameras
  • Automatic gain control
  • Backlight compensation
  • Wide dynamic
  • Infrared
  • True Day/Night
  • Thermal imaging

Cameras come in all types, sizes and configurations and choosing the improper camera for the scene could result in a poor image or no image at all. For example, many computer guys install infrared cameras indoors and outdoors thinking one size fits all. A camera is a camera, right? Read on…

While many infrared camera specifications say that the camera can see 30, 60 or even 240 feet, the actual produced image may be less than 2 feet from the lens.Why is that?

Take a grassy field for example.  An infrared camera may produce a satisfactory image. A parking lot can give an even worse image. Why is that?

Infrared cameras only see energy reflected from the subject, so this factor must also be considered. The larger the reflectivity value the better the image. The key factor is if the object has reflecting capabilities. Here are typical scenes and the reflectivity rates:

  • Snowy scene 85%
  • Glass windows and walls 70%
  • White matte paint on concrete 60%
  • Unpainted concrete, car park 40%
  • Red bricks 35%
  • Trees, grass and greenery: 20%
  • Empty asphalt area 5%

When installing an improper camera for the application, disappointment soon follows. The image below shows how an infrared camera performs when viewing a grassy field. The camera sees the building’s downspout but that is about it. This image is fairly useless and illustrates that this is the improper camera for the scene.

IRThis next image shoes what proper image should look like.

DNIn this same scene, the camera was replaced with a True Day/Night camera that has incredible lighting sensitivity. The camera was also moved on the opposite side of the downspout. We can now see the patio and the window off to the right just below the spot light.

While installing a camera system may seem to be an easy and simple task there are ramifications for not choosing the correct camera and installer. A professional security installer will be able to educate and guide you along the way so you will be able to see the benefits.