How to choose the focal length of the camera?

General household surveillance cameras are 2.8mm, 4mm, 6mm, 8mm, 12mm, 16mm or even 25mm. The focal length determines the sight distance and viewing angle. The smaller the focal length, the closer the viewing angle and the larger the viewing angle, and vice versa.

A lens with a focal length of 2.8mm can be used for the monitoring environment in a narrow space such as a storage room, generally within 3m, and 4mm can be used in a larger indoor environment, such as a small shop in the living room. , spacing of 3-5m, 6mm can be used for small shops or doorways, spacing of 5- 10m, 8mm can be used for outdoor roads and hutong scenes, and the best spacing is 10-20 m.

Matters needing attention in using camera focal length

How long the camera lens is selected depends on the spatial characteristics to be monitored and the shooting distance. The lens with each focal length can only achieve the best viewing effect within a certain range.

On the other hand, if you want to monitor a long distance and a wide range, the best way is to increase the number of cameras, or use an electric zoom lens to install with a pan/tilt, but this will be more expensive for ordinary people.

The above contents refer to Baidu Encyclopedia-Camera and Baidu Encyclopedia-Focus.