Camera types

If the video surveillance system to be installed is a new system, and no analog cameras exist, the best choice in most cases is to use network cameras, which are available in many different models to suit a wide variety of needs.

With such a wide variety of network cameras available today, most requirements across all vertical markets and system sizes can be accommodated. As with analog cameras, network cameras come in different models.

Fixed network cameras

Fixed cameras with a body and a lens represent the traditional camera type. In some applications it is advantageous to make the camera very visible. If this is the case then a fixed camera represents the best choice, since the camera is clearly visible, as is the direction in which it is pointing. Another advantage is that most fixed cameras have exchangeable lenses of C/CS type. For further protection fixed cameras can be installed in housings designed for indoor or outdoor installation.

Fixed dome network cameras

Fixed dome cameras, also called mini domes, essentially consist of a fixed camera pre-installed in a small dome housing. The camera can be easily directed to point in any direction. Its main benefit lies in its discreet, non-obtrusive design, as well as in the fact that it is hard to see in which direction the camera is pointing. One of the limitations is that fixed dome cameras rarely have exchangeable lenses, and even if they offer a choice of lenses, exchange opportunities are limited by the space inside the dome housing.

PTZ network cameras

Pan Tilt Zoom (PTZ) cameras have the obvious benefit of being able to pan, tilt and zoom either manually or automatically. For manual operation, a PTZ camera can, for example, be used to follow a person in a retail store. PTZ cameras are mainly used indoors and where it is desirable that the direction in which the camera is pointing can be seen. Most PTZ cameras do not have full 360 degrees pan, and are not made for continuous automatic operation, so called "guard tours". The optical zoom ranges from 18x to 26x.

Network dome cameras

Network dome cameras share the same benefits as the fixed dome cameras: they are fairly discreet and the direction in which they are pointing cannot be deter-mined when looking at the camera. A network dome camera, compared to a PTZ camera, adds the ability to pan 360 degrees. It also provides mechanical robustness for continuous operation in guard tours where the camera continuously moves between say 10 presets, day in and day out. With guard tours, one camera can cover an area where 10 fixed cameras would be needed to do the same job. The main drawback is that only one location is monitored at any given time, leaving the other 9 positions un-monitored. The optical zoom normally ranges between 18x and 30x. But for installations outdoors, zoom factors above 20x normally prove impractical because of vibration and motion caused by wind.

Non-mechanical PTZ network cameras

With the introduction of network cameras, a new breed of PTZ cameras are being introduced to the market – the so-called non-mechanical PTZs. Using a megapixel sensor, the camera can cover from 140 to 360 degrees and the operator can select to pan, tilt and zoom the camera in any direction without involving any mechanical movement. The key advantage is that there is no wear and tear on moving parts. It also offers immediate movement to a new position, which in a traditional PTZ camera can take up to 1 second. The best non mechanical PTZ cameras today are using a 3 megapixel sensor. In order to ensure a good image quality, pan and tilt should be limited to 140 degrees and zoom to 3x. For higher coverage or zoom the image quality will adversely be affected.

A number of variations of the camera types described above are available, and include:

Vandal resistant versions, depending on the protective housing used
Weather resistant versions, depending on the protective housing used
Day and Night versions, which means that the camera can automatically or manually switch between day mode with color video, and night mode with black and white low light image that can be enhanced by using IR illuminators. See Day & Night functionality.

Once the camera is selected, the next step is to select the appropriate lenses, housings, and any other relevant components necessary in the system. The installer should also be aware of a number of common practices related to camera positioning, which will help in obtaining the best quality out of the system.

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