In India, lenses are the most ignored part of the surveillance systems. Lenses for security camera are as important as eyes are for human beings. Surveillance system users always expect good and high quality cameras but we need to understand the all components in surveillance system including the lens are very important in getting a good image says Ashutosh Fotedar, Assistant Manager, Tamron India Pvt Ltd.
The resolution of the final recorded image is only as good as the weakest component in the surveillance system. The diagram shows the various components which play a vital role in getting a good image.
The important parameters to be considered while choosing a lens for the security camera are as follows:
1. Mount Compatibility
There are two kinds of lenses available in the market for surveillance cameras –
a) Built In/Board Mount lenses are integral parts of the cameras and used in Dome, Bullet IR, Zoom and PTZ cameras. These lenses are normally supplied directly to the camera OEMs and they develop the cameras accordingly. Cameras OEMs take special care of the mounting arrangements of the lens with the camera sensor. Even a small misalignment between the image sensor and the lens will result in defocused image at various zoom values. A user does not need to give much attention to it because camera and lens manufacturers work very closely so that best image results can be obtained.
b) C/CS Mount lenses are used with the box cameras and are externally attached to the cameras. To discuss more on this point, it is very important to understand C/ CS mount. It will be clear with the below diagram: The distance between the camera-lens flange surfaces to the CCD/CMOS is:
17.5 mm for C-mount
12.5 mm for CS-mount
So a C-Mount lens can be used with a CS-mount camera by using a 5 mm adaptor ring. CS-mount lens can be used only with CS-mount camera. Special care needs to be taken for the mount while selecting a lens for the security camera.