The lens of a security camera is like the cornea of your eye. Without it you can not see, and neither can the security camera. There are many different types of security camera lenses in the security camera market. The first division between lenses are the wide angle and the zoom lens. The next division is between the auto iris, manual iris, or no iris at all. These choices and others depend on the intended use of your security camera system. Correct security camera lens choice should be determined with your CCTV technician

There are many  factors involved in choosing a suitable lens are given on the CCTV Camera Lenses .