Your CCTV and its eye: the Lens

Many a time customers purchase an expensive CCTV Security Camera Kit and invest their energy, time and money to install it only to discover that the footage does not serve the purpose of installing the camera. 

 

It either looks too distant or is too close or does not cover the entire area.

What went wrong? Did you install the camera in a wrong place?

No.

Like any other Camera, one of the most important aspects of a CCTV Camera is the lens. And there are several parameters of a camera lens that must be met for a CCTV camera to be effective.

Let us take a look at the basics of a CCTV Camera lens.

1. Focal Length: The focal length of a CCTV Camera determines how much magnification the camera can provide. It is measured in mm and a camera with shorter focal length (e.g. 2.5mm) will provide a wide angle of view whereas a longer focal length (12mm) will provide a narrower angle of view.
2. Depth of Field: In simple terms, the depth of field will determine the distance within which the objects will be focussed. For example, in a large depth of field all the objects in the path will be in focus whereas in a small depth of field only a small section of the field of view will be in focus.
3. CCD Chip: Most CCTV cameras come in 4 different chip sizes 2/3", 1/2", 1/3" and 1/4".
4. Iris: Depending on where you will mount the CCTV camera, you may need to select a manual or an auto iris for the cam. A manual Iris lens is perfect for indoor use whereas an auro iris lens may be required for using outdoors.
5. F Stop/Aperture: F Stop or Aperture is the amount of light that the camera will allow depending on the focal length and the aperture opening.

A combination of all these factors will determine the final outcome of your CCTV footage. Without getting too technical about this, always understand that if you want to cover a very wide area like a parking lot, opt for a smaller focal length lens and mount it at a distance.

If you want to cover only a small area clearly, then opt for a higher focal length lens and mount it closer.