Important specifications when selecting a security camera are:

   Light Sensitivity   A camera's lux rating is the specification used to indicate how sensitive security cameras are to light. The lower the lux level the better.

   Resolution   At a minimum the resolution of a camera should be equal to or greater than the resultion supported by the DVR. Common resolutions are CIF and D1.

   S/N   The S/N ratio is one measure of a camera's quality. The higher the S/N ratio the better. Noise is caused by a poor camera, low light conditions, or bad wiring. A DVR has trouble with a noisy signal because noise is difficult to compress and therefore consumes much more processing power and disk space.

   Dynamic Range   A camera with a wide dynamic range is always desired, but is absolutely necessary when the scene has some dark regions and some bright regions. For example, a doorway to the outside presents a scene with some parts in daylight (very bright) and some in indoor light.

Security Camera Types

A traditional CCTV security camera can be used in a variety of situations. These cameras usually don't come with a lens, mount, or enclosure. Because these components are purchased separately, these cameras offer a very high level of flexibility. One disadvantage of this type of camera is it may be more expensive once it is configured, when compared to speciality purpose camera pre-configured for the situation.
A spot cam is a good general purpose security camera. It usually comes with an integrated varifocal lens and is designed to be used straight out of the box. You may need to purchase a mounting bracket. (more...)
A bullet camera is similar to a spot cam, but it usually has fixed focal length lens (not zoom) and is smaller and norrower than a spot camera. (more...)
A dome camera is mounted on the ceiling and is one of the most common security cameras used indoors. Dome cameras have two principle advantages. One, is that they are visually more appealing to most people. Two, the position of the cameras cannot easily be changed by hand. For example, tamper resistant cameras usually use a dome type layout for this vary reason. The disadvantage of a dome camera is usually related to performance. Most dome cameras do not have good low light characteristics and are not useful it the lights in the room are off. (more...)
A ip camera is directly accessible over the Internet. It's principle advantage is that it is a stand alone camera and does not require the use of a DVR. An IP Camera can be integrated with a NVR to build a video surveillance system. The disadvantage of an IP Camera is cost and configurability. (more...)
A ptz camera (Pan/Tilt/Zoom) provides the ability to "pan" (move on the horizontal axis), "tilt" (move on the vertical axis, and "zoom" (vary the focal length). The most common ptz camera is also an ip camera. (more...)
An infrared camera uses an infrared illuminator to allow illuminate the scene. What look like glass beads surrounding the lens are infrared LEDs that shine infrared light on the scene. (more...)
A pinhole camera is a small security camera used in covert video surveillance. About the size of a quarter, these cameras are hidden from view. There are limitations to these cameras that relate primarily to the lack of a full featured lens. (more...)
An auto zoom camera is high performance zoom camera that is remotely contolled. Unlike a ptz camera, an auto zoom camera does not allow the user to pan or tilt, but provides much higher optical performance. When combined with a mount that can perform the pan and tilt functions, the combined system is a high end system. (more...)
A video surveillance system can be deployed outside using a speciality camera housings. Key features are a blower (fan) to keep the camera cool in the summer and a heater for the winter (and to keep the glass from fogging up). (more...)
An outdoor dome housing is used for mounting externally. Obviously designed to accept a dome camera, the housing is frequently used when tamper resistance or PTZ is desired. (more...)