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Type of camera
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).
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 nightime there is a normally some light from the moon, stars, or street lights.
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.
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. Similarily, a 16mm lens is like the 4mm lens zoomed in 4 times.
Pen camera is an example of electronic miniaturization because it contains tiny versions of larger equipment, such as a still photo camera or an audio/video recording system. All of its inner components are connected by very narrow wires; a pinhole camera system is used with a small viewing lens near the top of the pen case. Besides a choice of video or still image capabilities in black and white or color, spy pen cameras are available with various memory capacities. The amount of memory corresponds with the number of stored photos or length of video footage a particular spy pen camera can hold. All of the working mechanisms of this spy device are hidden inside a case that not only looks identical to a ball point pen, but writes like one as well.
The Applications for CCTV
- Home Security System.
- Hidden in buses to control vandalism.
- Production control in a factory.
- Used by the stage manager of a show to see obscured parts of a set.