Archive for the ‘CCTV IR-illumination’ Category

How to Select a Night Vision Camera

Friday, April 9th, 2010

What you need to know about IR-illumination capabilities of CCTV cameras, and why the “green” movement makes them a new opportunity for security designers and integrators.

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Designers might want to check out the latest technological developments in cameras with built-in IR illumination as a potential add-on sale for both residential and commercial applications.

The night vision camera trend is being spurred partly by “green” initiatives because people don’t want to waste money on electricity to maintain outdoor flood lights.

Indeed, with enlightened ‘green clients’ you can sell the ROI for the installation of a night vision camera for exterior (or interior) security use vs. the cost of lighting.

How IR Illumination Works

Without any light source in some cases, cameras can clearly capture crisp images for use at night, potentially opening up a whole new market. CCTV cameras have always been primarily a commercial offering, but lower cost bullet and discrete dome units are well suited for resi applications.

IR illuminators offer the camera the ability, in essence, to capture the wavelength of light that is not visible to humans.

IR illuminators can be built into the camera or be a separate attachment. Generally there are three wavelengths of IR illuminators for night vision cameras:

  • 730 nm (nanometers) — Produces red glow about half the strength of stop light and offers the best visibility.
  • 830 nm — Most common strength that is used for semi-covert applications and produces a slight red glow.
  • 940 nm — Designed for covert applications. It can produce an image from full blackness, but can only view a short distance.

There are two types of IR illuminators:

  • Thermal IR — These detect heat. They are ideal for detection, but not for identification.
  • Active IR — These detect motion and offer crisper images.

Cameras are available that offer a combination of both technologies.

It’s a myth that if there is no light, there will be no picture. This is a  not generally correct, You can get a picture, but it’s not a good idea due to quality of the recorded images using the general product selection Low-lux cameras that are available for use in low-light situations.

However, these cameras, which do not have IR illuminators, are likely to produce a “noisy and grainy” picture. Also, if the images are being recorded on a DVR, they will take up a lot of space and bandwidth.

Likewise, if the images are being sent over an IP network, they require 40 percent more bandwidth for transmission.

Questions When specifing Low-Light Cameras

There are four key questions to ask with specifing a low-light camera:

  1. How far? Distance needed to capture images will determine focal length, beam angle and IR illuminator width.
  2. How wide? The wider the lens, the shorter the distance.
  3. Is there light at the scene? Some lighting looks good aesthetically, but is not good for image capture.
  4. What is the environment at the scene? Is the camera going to exposed to vibration, heat , saltwater, etc.

Night vision cameras themselves are getting greener. New units draw as little as 25 watts to 45 watts of power to see as far as 700 feet. Those same cameras used to require 500 watts to 1,000 watts.

Finally, designers should know that IR illuminators degrade at about 20 percent per year. Bosch has introduced a new technology called Black Diamond (pdf) to minimize degradation by automatically turning off the power to the illuminator during daylight hours.