CCTV security cameras are quite popular nowadays because of their efficiency as a crime-fighting tool. A surveillance system can be a powerful tool if you buy the right components and make proper selections when installing it. One of the most important aspects to understand is the coverage of the security cameras.

Range (How Far?)

Optical range is the distance at which a camera can capture the detail. Different cameras lenses have different ranges. Lenses are measured in mm, the larger the number the narrower the angle of view. Generally, 2.8mm or 3.6mm are considered wide angle. One thing to note here is that the angle of a CCTV camera should not be compared with a human eyes view angle because the real coverage can be completely different than what you think it should be.

CCTV cameras usually come with 4mm or 6mm lenses. Both offer different coverage.

4mm

4mm lenses have an effective seeing distance of up to 6-meters. The cameras with this size of lens are usually used under eave or on the way to provide coverage for a relatively smaller area such as a corner of your yard or deck, a back door, entrance, etc.

6mm

6mm lenses have an effective seeing distance of up to 10-meters. Surveillance cameras with this size of lens are typically used to provide coverage for driveways and entrances.

Field of View (How Wide?)

FOV (field of view) is the total height and width of the footage seen through a security camera lens. It is also known as the angular field of view or the angle of view. It is stated in horizontal and vertical degrees. Horizontal FOV represents the width and Vertical FOV represents the height of the view. When you combine both of these, you get overall FOV.

The FOV is also directly dependent on the lens of the camera, which is measured in mm. The concept is the same as mentioned before; the angle of view will be wider for a lower sized lens as compared to a larger one. For example, a 25mm lens will offer lower FOV as compared to a 4mm lens.

4mm

A 4mm lens offers a horizontal view of about 61.93 degrees in a CCTV security camera. So, you will be able to see up to 120 ft. wide area at a distance of 100 ft. with a 4mm lens. That coverage is pretty wide.

25mm

A 25mm lens in contrast, offers about 10.97 degrees of horizontal field of view in a surveillance camera. So with this lens, you can only see 19.2 ft. wide at a 100 ft. distance. Furthermore, at this distance the footage will have a ‘zoomed in’ effect.

Conclusion

In conclusion, the size of the lens directly affects the coverage of a security camera. That’s why it is recommended to check your requirements and purchase a CCTV camera with a lens size that is suitable for your required coverage.