CCTV Camera Lens and Focal Length Explained

Learn how focal length affects viewing angle, distance and identification when selecting a CCTV camera lens.

What focal length changes

Focal length affects the camera's field of view. A shorter focal length generally gives a wider view, while a longer focal length gives a narrower view that can cover a more distant target.

Wide view vs identification

A wide lens can be excellent for monitoring entrances, rooms and general activity, but the target occupies fewer pixels. A narrower lens can place more pixels on a distant subject, which may be preferable for identification at a controlled distance.

Do not choose by millimeters alone

Mounting height, sensor size, target distance and the exact camera model all affect the result. Use a field-of-view or focal-length calculator as a planning aid, then confirm the manufacturer's lens specifications.

Installation tip

Before final mounting, test the intended scene at the actual distance. Check faces, plates, entry points and blind spots rather than judging the lens only from its advertised viewing angle.