Surveillance cameras come in all sorts of different shapes and sizes but they all fall into two main categories: fixed and unfixed cameras. Unfixed cameras are also known as PTZ or pan, tilt, zoom cameras. Fixed cameras can be further divided into lens cameras and board cameras.
Fixed surveillance cameras:
Lens surveillance cameras consist of a camera body to which different types of lenses can be attached for a variety of surveillance purposes. That means lenses with varying focal lengths and apertures can be used on one camera giving it a flexibility that makes it popular for commercial use.
Board cameras don't have changeable lenses; instead the lens is fixed onto a circuit board. The fixed lens is usually of industry standard with either wide angle or pinhole aperture. Pinhole cameras are often referred to as spy cams as they are tiny and easily hidden in the home or office. Read the page on hidden surveillance cams to find out more about spy cams. Board cameras are quite limited but can be an economical surveillance tool in places such as homes or small offices.
PTZ surveillance cameras:
Pan, tilt, zoom cameras do exactly what the name suggests: the can rotate horizontally and vertically giving them plenty of movement and enabling the user to view a wider area than would normally be possible with a fixed camera. PTZ cameras can be controlled remotely via a connected controller or through a DVR or digital video recorder. Check out the digital surveillance page to learn more about these cameras.
PTZ cameras used to be expensive surveillance toys used only by those who could afford them such as large corporations, government agencies and casinos. Prices for these surveillance cameras have come down in the past few years making them more accessible to the general public. They can commonly be found hidden in a small dome-shaped casings that conceal which direction the camera is facing.
What to look for in a digital home video system:
The quality of the images produced is determined by imaging chips. These basically record the amount of light entering the lens and work in a similar way to film in a stills camera. There are two types of imaging chips: CMOS and CCD. The general consensus is the CCD chips produce a better quality image and the bigger they are the better. Unfortunately the bigger they are the more expensive they get. Also check who the chip was made by, Sony and Panasonic have the best reputations.
This refers to the level of light at which the camera will produce images of good or acceptable quality and this level is measured in 'lux'. Simply put, the lower the 'lux' rating the more light sensitive the camera. Surveillance cameras that are sensitive to light will be better able to cope with low light situations without compromising the quality of the image. Black and white cameras are, in some cases, cheaper and more light sensitive than color cameras. However, color cameras are coming down in both price and 'lux' ratings.
Digital surveillance systems can easily operate with analog cameras but digital surveillance cameras are also coming down in price. Digital cameras use a digital signal processing chip (DSP) to digitize the video stream from the imaging chip. The type and quality of this processing chip is important to the quality of the digital image
The number of pixels found on the CCD chip determines the resolution of digital cameras but in analog cameras the measurement for resolution used is 'lines of resolution'. The number of lines determines the sharpness of the image with 400 being a good resolution. Anything above this is considered high resolution.