The View is Better from up Here
Domes are effective in any installation where the viewing area is large enough that one camera cannot cover every viewing angle needed. Domes are excellent for situations where a wider field of view is required. They offer the most flexibility with their 360-degree by 180-degree adjustment capability.
Brian Curliss, product manager for Silent Witness, Surrey, B.C., explains that they offer accessories, such as the Wallmount, which extends the camera from a wall, and can be mounted near corners. This enables the camera to capture hard-to-see doors, windows and objects located in and around corners.
Typical installations include airports, department stores or parking lots, with installation positions mounted as high as possible without being obscured by anything hanging from the ceiling. "The surroundings where a dome is most viable is in largely populated areas where security visibility is required. Usually, in standard installations, the domes are effective if placed under overhangs where a wide angle of view is achievable. This enables good overlapping coverage with other domes placed strategically as well," says Dan McGinley, national sales manger for ELMO Manufacturing, Plainview, N.Y.
For outdoor use, light poles or high atop buildings are prime locations. "Anytime large areas need to be monitored, the choice is either install multiple cameras or a single dome. One of the advantages of a dome is that it can be manually controlled to follow suspicious activity or set up to operate on a duty tour where it will automatically patrol an area by moving on its own," says Bolotine.
As in all camera applications for security, lighting is the most critical component in determining what kind of camera is used. This holds true to domes as well. "Some of the more inexpensive domes will only perform in high light environments. Some only have fixed lenses, therefore lighting conditions such as blasts or bright light will cause images to bloom out. With auto-iris lenses incorporated into the dome, vari-focal lenses are pricey. But when we look at the poor performance of inexpensive domes, then the extra costs are justifiable," says McGinley.
And, with sensitivity to light, there are typically three types of camera options available in domes today: color, monochrome, or day/night. Color is the best choice for well-lit areas down to a considerably poorly lit area. Monochrome becomes exceptional because of it's sensitivity to infrared light, allowing the user, in many cases, to see better than the human eye. The day/night camera is a hybrid of these two; providing color images when light levels are high, and then switching to monochrome when it gets dark. With Silent Witness' MagnaView, features such as backlight compensation, electronic shutter and auto-iris have been integrated.
According to senior product manager for positioning systems and enclosures, John Ellenberger at Pelco, Clovis, Calif., a class of camera called integrated optics package (IOP), where the camera lens is one small integrated unit, is better suited for use in a CCTV dome.