Field of view for CCTV cameras references the range of vision you’ll have on the camera. It’s very important when selecting a CCTV camera. Field of view for CCTV cameras impacts how much of an area you can see, and in how much detail.
Think of it this way. Place your hands in front of you, palm facing palm, about a foot apart from each other. Everything you can see between your hands is your field of view. Maintaining their distance from each other (a foot apart), bring your hands to the sides of your head. You should have a hand beside each of your eyes. You can see pretty much everything you’d normally see in your vision.
Now bring your hands forward. They should still be a foot apart, one palm to the other. What you see between your palms is narrower. The distance between your palms hasn’t changed. You’re staring down a longer focal length. More of your vision is outside that foot of space between your palms.
Now extend your arms all the way. The amount of your vision that exists between each palm will be even lesser.
In the same way, a shorter focal length on a camera will allow you to see a broader range. For instance, a 10 mm focal length allows you to see most of a parking lot. This is useful to catch a great deal of action on one camera.
Extend that to a 50 mm focal length, and you won’t see the entire parking lot any more. You may capture one or two cars. This gives you less breadth of vision, but greater specificity. The detail will be considerably increased.
Make sure that you take field of view into account when selecting a CCTV camera. With greater resolution cameras like today’s 4k models, you can implement broad field of view while maintaining great ability to enhance detail. At the same time, maybe it’s more practical (and less expensive) to get two cameras with slightly lesser resolution, but a longer lens. You’d have to overlap their coverage, but you can maintain a similar ability to capture detail. The choice is different depending on precise circumstances or needs.