Zoom, means the ability of a camera to magnify a picture. Pan-Tilt-Zoom cameras and some fixed cameras have lenses that zoom in on an object. In other words, it magnifies the object of the video, such as a car in a parking lot,so that it can be seen in much better detail.
Zoom is a very important feature of video camera lenses. By making the image larger, it is possible to watch intrusions developing from some distance away from the doors to a building. When comparing thezoom features of a camera lens, it is absolutely critical tounderstand the difference between digital zoom and optical zoom.
Digital Zoom, It cuts out a section on a distant image,not actually getting you closer to the object but by magnifying the lack of clarity that already exists.
Optical Zoom, is like standing closer to the object, you can see it clearly.