Along with your surveillance camera, you need several peripherals to get your video surveillance system working.

Lenses

As with regular surveillance camera, the lens on a surveillance camera determines how wide an image is created and how much light is let in. Lenses are generally sold separately from cameras.

The lenses you purchase should match the format of your surveillance camera: 1/4" lenses work best with 1/4" cameras. It is possible to use a larger format lens than the surveillance camera calls for, but it is not recommended.

You also need to decide what type of lens you need. Fixed focal length lenses offer only one set field of view and are the least costly. To change the resulting image, you need to switch lenses. Variable focal length lenses and zoom lenses offer greater flexibility, allowing you to adjust your image's field of view. Motorized zoom lenses, the most costly type available, give you the ability to control your cameras remotely. If you want to zoom out for general surveillance and in for detail when you spot suspicious activity, motorized zooms are the way to go.

If you will be using the surveillance camera outdoors, look for a lens with an automatic iris. As in the human eye, the iris of a lens is what controls the amount of light coming in to the surveillance camera. Automatic irises can significantly improve performance for outdoor cameras, where light levels vary considerably. However, you can save money and use a manual iris lens when the scene illumination never changes, for example in an illuminated store or office.

Pan, Tilt, Zoom

For advanced security applications, you may want a pan, tilt, zoom (PTZ) camera. With the right equipment, a camera operator can pan (scan left and right), tilt (look up and down), and zoom in and out. The significant catch is the cost: PTZ systems are considerably more expensive than fixed cameras.

Housings

Cameras may need to be protected from potential vandalism or from the elements. Housings can range from simple coverings, to impact-resistant protection, to outdoor housings that include heaters and blowers for cooling. A more specialized type of housing is the dome: tinted Plexiglas hemispheres that prevent subjects from seeing which direction a camera is pointing. Choose the right housing based on the placement of the surveillance camera and its expected usage.