KEEP YOUR EYE ON THE CAMERA
Jul 1, 2002 12:00 PM
Trends in CCTV cameras are readily identifiable: an industry-wide shift from black-and-white to color; and technical and aesthetic improvements to CCTV cameras, including a variety of styles and sizes.
Quality at the lower end has also vastly improved. Difficult economic times have prompted some users to install multiple, inexpensive cameras that cover more area than a pan/tilt/zoom (PTZ) system.
Choosing a small static camera means fewer moving parts, which translates into less potential for breakdown.
Arron Stanley, owner of a Mail Boxes Etc. franchise in San Francisco, had a large CCTV camera watching the front door since the store opened a few years ago. Recently, he upgraded to a new system.
"The technology has vastly improved in just the past few years and prices have also come down," Stanley says. "My friend and I installed our three-camera, time-lapse VCR and Internet CCTV system in one weekend, and it cost less than $1,500."
The new system has not run into any problems. It was easy to install, and it provides Stanley with a new level of freedom and accountability. "Now I can watch my store from my home at any hour, day or night," he says. "It gives me great peace of mind because there's a video record of everything that occurs. The new cameras are ten-times sharper than the old one."
Stanley, like many independent business owners, has discovered that investing in a CCTV system ¡ª even a small one ¡ª is good business. He also learned that constructing a CCTV system starts with the cameras.
Selecting a CCTV camera is easier when it starts at a trade show or dealership, thus enabling a first-hand view of the available solutions and image qualities. Major considerations when purchasing a camera system include a good dynamic range, a high smear and a good signal-to-noise (SNR) ratio.
Dynamic range is the distance between the lightest and the darkest areas of an image. Generally, color cameras have a dynamic range of approximately 3:1, but it can be increased dramatically with digital signal processing offered by some camera systems.
Smear is the trail caused by a strong, moving light (a car headlight or a flashlight, for example) that enters the camera's CCD sensor. Smear becomes more evident as shutter speed increases, and the extent that a CCD sensor can reject strong light is called the smear rejection ratio.
Signal-to-noise ratio (SNR) figures are quoted in camera specifications. Most cameras have a SNR of about 40 dB, but more expensive cameras with resolutions of 480 lines or more may have a SNR as high as 60 dB. A device with a high SNR will produce images with less noise and sharper definition, no matter the environment.
As digital video recording and transmission over the Internet and local/wide area networks become more widespread, signal-to-noise becomes an even more important consideration. Digital technology makes everything sharper, even the noise that sometimes appears as "snow," and digitally-compressed files with a high SNR are smaller, so data retrieval on a network or the Internet is faster.
Most modern cameras are sold as complete units with lens and housing and CCD imaging hardware. Some systems allow the selection of different lenses depending on the desired area of coverage. Selecting the right lens is critical. The width of coverage of a scene at a given distance depends on the focal length of the lens and the size of the camera's CCD sensor (1/4-in., 1/3-in., or 1/2-in.). When choosing the focal length, consider the purpose of the system: Is it general observation to detect any activity, or is it the ability to accurately identify a person? A wide-angle lens may allow observation and detection of activity in a large area, but facial detail is limited. Selecting various CCTV housings, lenses and camera bodies can balance out the system to suit an end-user's needs.
"Being able to mix together various CCTV products from different manufacturers to provide the client with a surveillance video system that's tailored to his needs is getting easier all the time," says Michael Shaw of Web-Net Services Inc., San Leandro, Calif. "People are more concerned about security than ever, and because the cameras are now so small, folks are more comfortable with them. It costs less as well."
CCTV is becoming more flexible overall, and today's cameras are no exception. Silent Witness, Surrey, B.C., features a modular CCTV camera system, which includes choices among 13 housings, 10 camera boards and nine lenses. When a customer buys a camera, there are more than 1,100 different combinations, allowing the choice of specific housings, camera boards and lenses for any given situation.
A MERGING OF TECHNOLOGIES
"The diversity of applications continues to grow, and CCTV cameras are getting smaller. I'm particularly impressed with the defense technology transfer that has occurred in the last decade," says Ronn Rohe of Cohu Electronics, a San Diego-based CCTV manufacturer. "Besides security, we're active in the machine vision and advanced imaging market. The new generation of cameras and software utilizes technology that was developed for military purposes, and has now migrated to common industrial CCTV use. Real-time image analysis, night vision, and wide area detection are examples.
In addition to the transfer of high-tech solutions, an increasing cost-to-benefit ratio gives CCTV buyers more incentive. Once rare technology, significant miniaturization of cameras is progressing without a price increase. "Every time you think that a CCTV camera can't get any smaller, it gets smaller," Rohe says. "The small size doesn't necessarily limit the features, because the evolution of digital signal processing has added more functionality."
Cohu Electronics' i-Dome camera is half-camera and half-dome, and it is typical of the industry's technology convergence. Products are becoming available with day/night visual range, better resolution, reduced size and weight, modularity and the ability to take advantage of the increasing use of the Internet.
Sanyo Security Products, Chatsworth, Calif., has taken the all-in-one approach one step further. Introduced at the 2002 ISC Expo West in Las Vegas, the DSR-C100 includes a hard drive within the camera itself. The camera was designed for security applications, and according to Sanyo, banks, convenience stores and schools are suitable applications. It continuously records 17,000 high-quality digital images on its internal 10.2GB hard drive. At three pictures-per-second, the moving pictures are comparable to the resolution of 35mm film, ensuring detailed and clear images, which makes identification simple. The camera, which connects directly to a PC, can record on Compact Flash (CF) cards for transportation and back-up. When an incident occurs and the alarm mode is activated, the unit will record and store up to 90 minutes of video. In playback mode, the operator can choose a zoom function to enlarge the image as much as 21 times. A watermarking capability ensures digital editing protection and helps address chain-of-custody issues when using the video images for law enforcement purposes.
LOW LIGHT, NO PROBLEM
Today's CCTV cameras have better dynamic range with full daylight and nighttime imaging capabilities. Companies such as Sony, Panasonic and Toshiba have new cameras able to produce acceptable color images in light as low as 0.1 Lux ¡ª equivalent to the light of a full moon.
Toshiba has introduced Xtrene Light Imaging, a technology that provides a dynamic range 133 times that of a normal cameras. The camera also has a special automatic shutter that adapts to light changes in real-time. There have also been advances for cameras and lens add-ons with thermal and infrared capabilities.
With a life span of 10 to 15 years, choosing a CCTV system is a decision you'll have to live with for a long time. Picking the right cameras and accessories can make the decision a lot easier.
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 SRO Magazine, a publication covering the stage and A/V rental markets.