What does Varifocal mean?

If a camera is equipped with a vari-focal lens, that means its focal length can be adjusted anywhere between its designated range.

The Focal Length determines the field of vision.

The smaller the focal length, the wider the field of vision.

Take a look at the images below. Look how the church seems to zoom in as the size of the lens is changed.

The camera is the same distance from the church in each photo. A person can zoom in on the subject. Notice the sides of the street show less the more the camera zooms.

The principle is to adjust for the greatest amount of zoom effect, and therefore the most detail, and still cover the width of the field of vision desired.

Below, the photos shows the actual width of the field of vision at different lens settings but at the same distance.

It is important that you choose a camera with varifocal lens technology if you are new to the technology and want to have your first project a success.

CCTV Lens Comparison Chart

CCTV lens
Focal Length	Angle
2.5mm	120°
3.6mm	92°
4.3mm	78°
6.0mm	53°
12mm	25°
25mm	18°