is a tilting vertical mast that can be used in those situations where the
cantilevered mast is not appropriate. Two cameras can be mounted atop a
vertical mast. The tilting feature permits the top of the mast to be lowered
to working height for maintenance on the ground. Counterweights facilitate
the tilting operation of both the cantilevered and vertical masts. One other
support is provided that permits mounting a camera to the side of a building
or other vertical surface. The following summarizes the available camera
Standard Video Camera. The standard vidicon tube is the most
widely used image tube for CCTV. Conventional cameras are designed primarily
for daylight. These cameras typically operate at light levels of 1 lumen per
square meter. Their spectral response closely approximates the human eye.
In continuous 24-hour use, it will last up to 6 months. A typical CCTV
camera is illustrated in Figure 27.
Low-Light Level Camera. Low-light level cameras can be used
to provide greater sensitivity when required, i.e., much less lighting than
the standard vidicon. These cameras also generally have a longer life.
Automatic iris control is needed to prevent "blinding" of the camera in