It hasn't been that long since we have had the advantage of using a security camera online. Before the proliferation of the Internet, security cameras at best, sent their images wirelessly using a radio frequency transmitter to repeaters (receiver/transmitters that would keep the signal viable and pass it along to its destination) or directly to a nearby monitoring company.
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 closed circuit security camera has been used for decades. But when the digital world began to affect the digital video security and surveillance world, it opened up numerous new features never available before that made this type of system versatile, powerful, and simple and easy to use.
One of the most popular digital video security system features is the zoom CCTV or Closed Circuit TeleVision. There are many different types of Zoom CCTV cameras designed for a multitude of uses; be sure when shopping for one that you get the features you need.
A multichannel security camera usually refers to a wireless security camera that has more than one frequency that it can transmit its video (and audio for some) data over to a corresponding receiver. The multichannel aspect is important to prevent cross talk, interference, or other reception problems.