In the world of security cameras, 18x zoom can be equal to 36x. More specifically, a high-resolution security camera with 18x optical zoom can provide images that, for surveillance purposes, are just as, or even more useful than those delivered by a standard resolution, 4CIF camera with twice the zoom capability.
The pixel resolution in both cases is virtually the same: the newspaper's name, for example, is readable. However, the HDTV camera offers the same details with just half the zoom capability of the standard-resolution camera.
It is also important to note that the HDTV camera's wider (16:9) field of view makes it possible to monitor a larger area without compromising image details. In the image from the 4CIF camera, only one person can be seen in the picture, while in the HDTV image, the operator can see more than one person and simultaneously pick up small details such as texts on the newspaper. So while the level of detail is similar, the HDTV 720p camera enables more of a scene to be seen, which is advantageous in surveillance situations. The wider field of view in zoomed-in mode also makes tracking easier and more reliable since the risk of losing sight of a person or object while panning or tilting the camera is reduced.