Introduction to CCTV Monitoring

What is CCTV?

Most people think that CCTV is a relatively new invention, but then again, many don’t even know what it is ... so first things first, what exactly is Closed Circuit Television? Well the television bit is perhaps self explanatory; it’s simply about putting a picture onto a television screen, or ‘video monitor’ to give it its correct title. Incidentally, very basic video monitors are essentially televisions, but without the additional circuitry needed, to receive and decode the Radio Frequency signals, which are transmitted through the air.

The Closed Circuit’ bit is actually quite straightforward. Let’s say for example, that you subscribe to Satellite TV. If you watch your favorite television programmed, you and perhaps a few million others will be able to receive the transmitted signal through the dish and ‘set top box’. As anyone with a correctly tuned ‘Telly’ can access this signal, we can safely describe this type of arrangement as an ‘Open Circuit Television’ or ‘OCTV’ system.; If a signal is being linked from any source, whether it’s a DVD player, a camcorder, or a surveillance camera, directly to a display device such as a television, this is described as a ‘Closed Circuit’ simply because it is not available to anyone else.

So you can see that in the early days of developing video camera security systems, the pictures from the cameras were almost always sent to a monitor, or a video recorder, or indeed a sealed Control Room under ‘Closed Circuit’ conditions, hence the now widely accepted term “Closed Circuit Television”.

Which type of Security Camera should I use?

A security camera can come in many different styles including dome, bullet, infrared and c-mount.  The security camera that will work best for your application will depend on several factors such as whether you will use the security cameras inside or out, during the day, nighttime, or both.

Bullet style security cameras are the most popular. They can be used inside or out. These security cameras come in black and white or color and come with all of the required mounting hardware. Some security cameras casings are weather resistant and don’t require added external protection. Most security cameras have a fixed 6mm lens that allows you to see facial features out to about 30 feet and provides a 56 degree angle of view.

Resolution levels for black and white security cameras are about 400 lines, any higher and the benefits are minimal. For color cameras, the higher the resolution the better. 

Infrared security cameras are also very popular as they allow an image to be seen in little or no lighting conditions. Most infrared security cameras are bullet style and can be used inside or out. The cameras have infrared lighting installed around the outer edge of the lens which allows the security camera to see in no light.

The advantage to c-mount security cameras is that the lens can be changed. You’ll want a special camera lens if you need to see further than 35 ft. The colour c-mount security camera allows you to change lenses on the camera giving you the ability to zoom into a particular area. Varifocal camera lenses allow you to adjust the focus from 5 to 50 mm. These lenses can be used inside only unless you put it in special housing for outdoor use.

Dome security cameras basically provide a different look. Everyone has seen these security cameras in businesses and stores. Because of its shape, its difficult to tell exactly where the camera is aiming unless you see it up close. Dome cameras are generally used inside buildings.

Dome Cameras

The dome camera is obviously named for its dome shape. Everyone has seen these security cameras in businesses and stores. Because of its shape, its difficult to tell exactly where the camera is aiming unless you see it up close. Dome cameras are generally used inside buildings, although the armor domes can be used outside as well (more about the armor dome below). You can mount them on the ceiling or on a wall. They are available in black and white (b/w) and color, and the basic unit has good video resolution (400 lines for b/w, 380 for color).

Varifocal dome cameras feature the highest quality SONY 1/3” Super HAD CCD sensor and excellent resolution (420 lines). The 5-8mm model has an adjustable lens focus from 5mm to 8mm. The 9-22mm model can adjust its lens focus from 9mm to 22mm.

Infra Red Cameras

An infrared security camera has infrared LED lighting (light from a different region of the electromagnetic spectrum than we normally use to see) installed around the outside of the lens of the camera. This lighting allows the camera to capture a good image in no light at all. With a little bit of light (called low light) the infrared camera can capture a picture that looks just like daytime. People use infrared security cameras for businesses that have the lights out at night (in case of break-ins). Or for outside, nighttime viewing. Keep in mind that even at nighttime there is a normally some light from the moon, stars, or street lights.

Infrared cameras are often called “Night Vision” cameras because they can ‘see’ at night. However, do not confuse “Night Vision” with “Day / Night Cameras”. Day / Night cameras do not have infrared lights built in. More about those types of cameras below.

Infrared security cameras will provide a color picture while the light is good. When it gets dark, the camera will switch to infrared mode and illuminate its built-in infrared LEDs. In infrared mode the image is captured in black and white - this is true of all infrared cameras. The level of light required to capture a good picture is referred to as a camera’s lux, the lower the lux the better the camera can see in low light. For example a camera with 0.003 lux is better than a camera with 0.2 lux. Infrared cameras are considered to be 0.0 lux in infrared mode - in other words they can ‘see’ with no light at all.

Infrared cameras are also compared by how far they can see in total darkness. This is generally a result of how many infrared LEDs are built into the camera. Our Long Range Color Day/Night Weatherproof IR Camera can see up to 150ft. with no light at all.

If you are going to use an infrared camera outdoors, its best to use a outdoor weatherproof bullet style camera. This is because if you use an indoor infrared camera and need to put it in an outdoor housing, sometimes the infrared light reflects off the glass of the housing. Some people get acceptable results if the camera is absolutely flush up to the glass thereby reducing the glare. An alternative solution is to use a day / night camera which has an extra sensitive imaging chip that allows it to capture a good picture in low light situations without using infrared lighting. This works well for example if there are street lights outside or an exterior light that can be left on at night.

Bullet Cameras

The term Bullet Camera comes from its resemblance to a rifle bullet. Generally long and tapered like a cylinder, it looks like an oversized ammo cartridge.

Most bullet cameras come with a fixed 3.6mm lens that allows a 80 degree angle of view. This is the widest angle you can have without distorting the picture. A 4mm lens will allow you to see facial features out to about 35 feet. If infrared is included you can generally see 35 feet minimum with no external lighting, some can see up to 70 feet.

Some devices capture images in color which is best for daytime lighting. For nighttime viewing choosing an infrared camera, which captures images in black and white is better. Many of the products will display color during the day and automatically switch to black and white infrared viewing when light levels are low. Resolution levels for black and white are usually about 400 lines, any higher resolution and the benefits are minimal. For color, the higher resolution the better the picture.

Used in closed circuit television applications, bullet cameras contain essentially the same electronic components as c-mount cameras but have been modified to fit in a weatherproof casing for outdoor use. You can see from the image that some models allow the housing to be removed for installation indoors. Mounting brackets are included with each item. They can be installed on the ceiling or the wall. Voltage is 12V DC. Power adaptors are included with every camera.

C-Mount Cameras

The advantage to a c-mount camera is that the lens can be changed. If you need to see further than 35 or 40 ft then you’ll need a c-mount camera with a special lens. C-Mount lenses are available from 4mm to 50mm. A 4mm lens provides facial detail and a 70 degree angle of view focused up to about 35 ft. An example of where you might use a fixed 4mm lens is in a small office, or at home to focus on your driveway.

A higher millimeter lens will provide further distance, but narrows the field of view. So, a 16mm lens would provide about a 15 to 20 degree angle of view at a focus distance of about 35 ft (or a 70 degree angle of view at about 140 feet). In general, a 8mm lens is like a 4mm lens zoomed in 2 times. Similarly, a 16mm lens is like the 4mm lens zoomed in 4 times.

Many times, the best option is to use a Varifocal lens. This will allow you to vary the focus from 5 to 50mm. So when you install the camera you can fine tune the focal distance and angle of view. An example of where you might use a Varifocal lens is outside (or inside) a large commercial building where you need more distance than 35 ft. and the Varifocal lens will allow you to adjust the focal distance to your preference.