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At OHWOAI Surveillance, we understand the importance of choosing the right focal length for your surveillance camera requirements. Focal length measures the distance from the optical center of the lens to the camera's CCD/CMOS sensor and plays a key role in determining the image size, viewing range and depth of field.

Field of view and depth of field Field of view refers to the maximum observable area formed by the two edges of the lens, while depth of field indicates the range of distances at which an object can be captured sharply.

Effect of different focal lengths In today's era of network surveillance cameras, commonly used focal lengths are 2.8mm, 3.6mm/4mm, 6mm, 8mm, 12mm, even 16mm. Some cameras even have variable zoom capabilities. So what difference does different focal lengths bring?

Here is a brief explanation:

✅ A large focal length allows for long distance observation, but reduces the viewing range.

✅ Small focal length allows close-up observation and provides a wide viewing range.

✅ A larger focal length provides more detail but reduces the observed field of view.

✅ With the same focal length, objects at greater distances can be captured with a wider field of view, but the recognition accuracy will decrease.

✅ A larger focal length is required to capture faces and bodies clearly from a greater distance.

When choosing the right focal length for your surveillance camera, it is important to consider the following factors:

Monitoring range

The focal length of a surveillance camera determines the size of the surveillance image and the effective viewing distance, which is the surveillance range.

☆ If you need a wider field of view in a smaller surveillance area, such as a residential living room or a small retail store, cameras with a focal length of 3.6mm or 4mm are suitable. These lenses have a viewing angle of 75° to 90° and can cover a space of 40² to 80².

☆ If you need a larger surveillance area, say a space larger than 10m x 10m, you will need a camera with a larger focal length. However, the corresponding viewing area will be smaller due to the larger focal length. Consider using a pan-tilt-zoom camera or installing multiple surveillance cameras to achieve comprehensive surveillance.

☆ If you need to cover a very long distance with a fixed surveillance range, for example monitoring a parking lot 30 meters away, please choose a camera with a focal length of 12mm or more.

Usage Scenarios

The choice of surveillance camera is often driven by the requirements of a specific scenario. If you don't want to get too involved with the complex parameters of focal length, you can roughly determine the focal length of your camera based on the following usage scenarios:

✅ For small, constrained spaces like garages and warehouses, we recommend the 2.8mm focal length, which provides optimal surveillance within 3 meters.

✅ For indoor home environments and small retail stores, we recommend a 4mm focal length that provides optimal surveillance at 3-5 meters.

✅ For outdoor scenes such as your home garden, balcony or entrance, a 6mm focal length is recommended to ensure optimal surveillance at 5-10 meters.

✅ For outdoor locations such as roads and alleys, 8mm focal length is recommended to provide optimal surveillance at 10-20 meters.

✅ For some fixed long distance surveillance, 12mm focal length is recommended to provide optimal surveillance within a range of about 20-30 meters.

✅ Some cameras come with an adjustable focal length feature, allowing you to customize the size of the lens to suit the scope of your surveillance scene.

OHWOAI Surveillance offers a wide range of surveillance camera systems to suit your specific needs, including indoor and outdoor IP camera modules, PoE security camera sets, wired security systems, commercial security camera systems, outdoor NVRs, Funlux 4-pack security camera sets, PoE home surveillance systems, and Zmodo NVR PoE solutions. Our advanced technology and comprehensive product lineup allows OHWOAI Surveillance to provide quality surveillance solutions for your peace of mind and security.