Video Surveillance Buyer's Guide
Choosing surveillance cameras
Table of Contents
- Introduction to video surveillance
- Evaluating your CCTV needs
- Choosing surveillance cameras
- Surveillance camera peripherals
- Choosing surveillance system monitors
- Security system recording with DVRs
- Connecting CCTV surveillance cameras
- Choosing a CCTV vendor
- Video security system pricing
- Security camera buying tips
- Find a Video Surveillance Systems supplier
The basic technology behind most surveillance cameras is the Charge Coupled Device (CCD). CCDs convert images into electronic impulses. In doing so, they provide a good combination of low price and quality picture for security applications, greatly improving the resolution of a modern camera when compared to older technologies.
Camera formats are measured in inches, with most varying between 1/4" to 1". This refers to the usable image size created inside the camera. For standard security, a small size is fine -- which is why 1/4" and 1/3" cameras dominate CCTV sales. Larger formats like the 1/2.5" can result in better images, jumping up from a 1.3 megapixel image to a 2 megapixel image. Used in large industrial applications, cameras of this size are also found integrated into the latest IP-based monitoring systems.
Many surveillance cameras also use digital signal processing (DSP) to convert analog video to digital information, improving picture quality and boosting functionality.
Color vs. black and white
Many businesses opt for color cameras over black and white models due to a recent and significant drop in price. For security and evidence purposes, color cameras are better. In fact, some vendors don't even sell black and white cameras any more. After all, sending police after "the man in the blue coat" is difficult when you can't tell what color the coat is.
While black and white cameras can operate better than color cameras in extremely low light situations, most small- to medium- sized businesses use CCTV in well-lit indoor environments, making them ideally suited to color cameras. In addition, many high-quality color cameras today can switch to black and white when necessary.
Resolution refers to the level of detail in the captured image. The measurement to look for is horizontal TV lines (TVL). A normal surveillance camera picture is around 330 to 400 TVL, with high-resolution getting up to 550, 600 and even 700 TVL. Don't be swayed by pixel measurements in the hundreds of thousands. TVL is a more consistent measurement.
Upgrading your cameras can cost as little as $100 to 150 per unit.
But when considering an upgrade, make sure your entire system is capable of supporting the new resolution. For example, if your security recorder captures 330 lines and your monitor displays 400, upgrading to a camera capable of 600 TVL is useless as the improved resolution will be lost in the conversion. In the end, the small cost to upgrade your camera may be multiplied by the costs to upgrade other equipment.
Signal to noise ratio (s/n) indicates how much "signal," or actual picture information, the camera transmits, as opposed to "noise," which comes across as static. An s/n ratio of 40db indicates that the signal is 100 times the noise, which results in an acceptable picture with some fine grain or snow. 30db results in a poor picture, and 60db produces an excellent picture with no static visible. However, noise can also be introduced by other components in addition to the camera, including nearby electronic devices, machinery and wireless signals.
Sensitivity to light is measured in lux. The lower the lux, the less light you’ll need to capture a clear image. For example, a sensitivity of 2 lux means the camera can see fairly well by the light of a 40W fluorescent bulb. On the other end of the scale, a 0.5 lux rating indicates the camera can actually see better than the human eye in dark settings, making it ideal for nighttime surveillance. Though your needs will depend on available light in the area being monitored, lux ratings should not be the most important aspect of your camera decision.