Selection of Lens Focal Length for Video Surveillance Cameras

Focal length

The distance from the principal point on the rear of the lens to the optical axis of the imaging plane is the focal length. The smaller the value, the wider the shooting range (wider angle of view).

Focal Length

后侧主点：Rear Principal Point 镜头：Lens 焦距：Focal Length 摄像机：Camera 成像面：Imaging Surface

Perspective

When the same lens is installed on cameras of different specifications, the viewing angle will also change, so the above table shows the reference viewing angle values of cameras with the same lens target size.

Visual Angle

Object height, width, object distance and focal length

Object Height

Reference data

Taking the lens with 1/3 target surface as an example, the viewing angle of the 2.8mm lens is about 90 degrees, and the visual distance is 6-8 meters. The viewing angle of the 3.6mm lens is about 80 degrees, and the visual distance is about 8-10 meters. The 6mm lens has a viewing angle of about 60 degrees and a visual distance of about 12-15 meters. The 8mm lens has a viewing angle of about 45 degrees and a visual distance of about 16-20 meters. The viewing angle of the 12mm lens is about 25 degrees, and the visual distance is about 20-25 meters. The viewing angle of the 16mm lens is about 22 degrees, and the visual distance is about 25-30 meters. The 25mm lens has a viewing angle of about 15 degrees and a visual distance of about 35-50 meters.