LOOMING PRESENCE
 
LOOMING PRESENCE

Jun 1, 2002 12:00 PM
By TOM PATRICK MCAULIFFE

Whether internal or external, thieves can put a real dent in a business. Video surveillance and public notification that an area is being videotaped are important tools in monitoring business and deterring crime. Today's CCTV outdoor and dome camera enclosures are virtually indestructible and provide protection from vandalism and the elements. Better still, security video domes are not that expensive and can make a thief think twice.

Each solution ! outdoor enclosures, outdoor domes or interior domes ! has its advantages.

Outdoor CCTV camera enclosures are rugged boxes that pan and tilt while protecting cameras from the weather. Domes ! those round half-circles common in Las Vegas casinos ! can keep suspects guessing because it is difficult to see which way the camera is pointing inside the dome. To help them blend in, different dome colors are available to make the surveillance units even more discreet.

Outdoor enclosure and dome CCTV camera expert John Ellenberger, senior product manager in the Positioning Systems Division at Pelco Corp., Clovis Calif., offers some insights in the following interview.

Q: What should a facility consider when choosing a dome camera unit for outdoor use?

Ellenberger: "There are three main things. The first is weatherability ! the dome system should be compliant with NEMA 4X and IP66 standards. These are standards to ensure no water or dust will get into the enclosure. The dome system should also be rated for the temperature extremes it will be subjected to. Manufacturers include these ratings in their specification sheets.

"Second, look for light sensitivity. Dome systems can reproduce images that cannot be seen with the human eye, so they can be used in applications that were not possible just a couple of years ago. Some dome systems achieve high light sensitivity by switching to a black-and-white mode in low-light levels. Others digitally extend the shutter time in low-light levels to achieve better sensitivity. With the longer shutter time, the picture can become slightly blurred with fast motion, but the color content is preserved, giving the security professional monitoring the scene more information to make a positive identification. The camera that goes to black-and-white mode provides better motion (less blur) but loses the color content of the image. So the designer of the system has a choice, to optimize the performance of the system for motion or color.

"Third, look for a dome system that features good angle of view. The zoom ratio of the camera is often used as a comparison of one system to another. While this is important, it's also important to consider the angle of view at both extremes of the zoom range. Because of where the dome is mounted, and what the desired scenes may be, some applications require a wide angle of view and others demand a very high telephoto capability. The correct specification to determine the best choice for your installation is found in the angle of view measurements."

Q: When comparing a dome to a traditional pan/tilt/zoom camera enclosure, which is better and why?

Ellenberger: "Dome systems give a high degree of discretion not found in traditional pan and tilt systems. Because the unit is enclosed inside a dome, it's very hard to see where the camera is pointing. In addition, dome systems from most manufacturers have better performance than their traditional pan-and-tilt systems. Features such as auto-focus cameras, extremely high positioning speeds and advanced programming features are necessary.

"Many dome system manufacturers are now offering ruggedized dome enclosures. They typically have key locks to make access into the enclosure more difficult, use thicker material for the dome enclosure and use slightly thicker material for the dome bubble. In addition, Pelco offers a version with an optional cage around the bubble for added protection against vandalism. The cage bars are spaced to provide very little interference with the picture when in wide angle, and actually disappear when the camera is zoomed to about half of its zoom ratio."

Q: Will domes and enclosures ever be bulletproof?

Ellenberger: "The issue with trying to make a dome or enclosure bulletproof is that there is a very large impact on the cost and clarity of optics. Because the camera moves inside of the dome, and has very high zoom ratios, the dome bubble needs extremely high clarity in all areas of the bubble. To make a dome bubble completely bulletproof, the bubble has to be significantly thickened and made of a different material, which reduces the clarity and significantly adds to the cost. Dome systems that claim to be bulletproof are available, but are not widely used."

A former editor of Government Video magazine and U.S. Navy photojournalist, Tom Patrick McAuliffe is a contributor to Access Control & Security Systems and also writes for Video Systems, a sister publication.


 
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