Surveillance Camera Lenses

eSSL Security

A CCTV Camera is only as good as its lens. The lens will determine how far and much detail the CCTV camera can see. These lenses are actually image sensors that convert an optical image into an electronic signal. The most commonly used sensors in CCTV cameras are:

•          CCD (Charge-Coupled Devices)
•          CMOS (Complementary metal–oxide–semiconductor)

Each cell of a CCD image sensor is an analog device. When light strikes the chip it is held as a small electrical charge in each photo sensor. The charges are converted to voltage one pixel at a time as they are read from the chip. Additional circuitry in the camera converts the voltage into digital information.

A CMOS imaging chip is a type of active pixel sensor made using the CMOS semiconductor process. Extra circuitry next to each photo sensor converts the light energy to a voltage. Additional circuitry on the chip may be included to convert the voltage to digital data.

CCD sensors use TVL (Television Lines) to measure the resolution, while the resolution of a CMOS sensor video is measured in MP (Megapixels). 480TVL≈1.3MP (approx.)