Surveillance camera lens are slowly beginning to evolve with the technology that supports them. Before the digital age, a good majority of the surveillance cameras required that a lens be purchased for each camera. Presently, some cameras still work that way, but the vast majority has the lens built right into the camera. These lenses are often referred to as "board lenses."
The dome security camera is one of the most popular types of digital video security camera in use today. Thanks to modern technological advances a lot of electronic power can be packaged inside a small 3.5 inch diameter dome camera. Not only are they small and powerful, but the average dome security camera is light weight as well (in most cases weighing just under one pound), which makes it easy to mount just about anywhere.