How to Choose the Monitoring Focal Length

As security equipment continues to evolve, surveillance devices come in a variety of models. Depending on the installation environment and usage scenarios, there are numerous styles of surveillance. Many friends are unsure how to choose the surveillance focal length when selecting a surveillance camera. Today, Wuxi Dihang Technology Co., Ltd. introduces some key considerations for choosing the surveillance focal length.

Based on the scope of monitoring:

Today's surveillance options are vast, with earlier systems featuring fixed focal lengths. However, modern surveillance systems allow manual control of the image. The focal length of a camera determines the size and distance of the monitored area. For indoor installations with a smaller surveillance range, opt for a camera with a narrower focal length, such as 3-6mm. These cameras have a照射 distance of up to 10 meters, but offer a wider viewing angle of 45-70° or more, making them ideal for indoor or small-area surveillance.

Choose according to the installation environment:

In essence, apart from some high-end surveillance cameras, most surveillance lenses have a fixed focal length. The choice of surveillance focal length varies depending on the installation environment.

For outdoor environments, if the installation is complex and the distance is considerable, a camera with a longer focal length is necessary. Taking a 12mm to 16mm surveillance camera as an example, cameras within this focal length range are suitable for monitoring distances of 20 to 50 meters. However, due to the longer focal length, the field of view is significantly reduced, typically around 15 to 30 degrees.

If the monitoring area is rectangular and the distance between the monitoring area and the camera is considerable, a camera with a long focal length is the most suitable choice.

Based on User Needs:

The size of the focal length affects the overall performance of surveillance cameras. A larger focal length value means the surveillance area is wider, but the angle of coverage becomes smaller; conversely, a smaller focal length value narrows the surveillance area, but significantly increases the angle of coverage.

When selecting the focal length for surveillance, it's best to choose based on the user's needs. However, when choosing surveillance equipment, one should not only consider the focal length but also clarity and other features. Some surveillance cameras change their clarity along with the focal length. Generally, cameras with a shorter focal length are suitable for close-up shots, while those with a longer focal length are better for long-distance shots.

Typically, a short focal length surveillance camera is used within a 10-meter radius, a medium focal length camera for a 20-meter radius, and a long focal length camera for a 50-meter radius. However, due to varying focal lengths, the coverage ranges differ. In cases where the monitoring area and installation environment are uncertain, the provided options are theoretical and intended for reference only. Most often, a network of multiple surveillance cameras is used to cover the monitoring area, hence the focal length selection varies accordingly.