| What is CCTV field of view and why is it | | | | finding the height and width it is important to |
| important? Field of view is really about what you | | | | know the distance. The distance will be the final |
| will be able to see through a security camera lens. | | | | determining factor in how wide the camera will be |
| The field of view (or FOV) is the total height and | | | | able to see. |
| width of the view seen through the CCTV | | | | It is also important to note that security camera |
| security camera lens. It can also be referred to | | | | lenses are measured in mm. To get a wider angle |
| as the angle of view or the angular field of view. | | | | of view you need a lower number of in terms of |
| The angular field of view is stated in horizontal | | | | mm size of lens. For instance a 4mm lens is a |
| and vertical degrees. The question is degrees of | | | | much wider lens than a 25mm lens. The view |
| what? Well it is degrees of a circle. Imagine a | | | | from the 25mm lens is much more narrow which |
| circle if you will with a section marked out of it | | | | also works to make images farther away look |
| like a piece of pie. That section of pie is the | | | | closer or have a better resolution. |
| "degree" of view. A full circle is 360 degrees. A | | | | Now for some examples: A 4mm lens would |
| piece of pie in the circle would take about maybe | | | | have a horizontal degree of view of |
| about 45 degrees. In the world of CCTV then this | | | | approximately 61.93 in a security camera. A good |
| is a 45 degree field of view. Imagine yourself in | | | | example of this would be what you can see if |
| the center of the circle looking in one direction. | | | | you closed one of your eyes and only looked out |
| Your view would be like a piece of that pie out of | | | | the other. Looking out one eye is approximately |
| the circle. | | | | the same as a 60 degree field of view. At a |
| That degree of view must then be translated into | | | | distance of 100 feet with a 4mm lens would be |
| a linear measurement. Meaning how wide and how | | | | able to see 120ft wide. That is a pretty wide shot. |
| high of an area will the camera and lens be able | | | | If you used a lens that was 25mm in length |
| to see in actual feet or inches? The Horizontal | | | | instead the horizontal field of view is 10.97 |
| FOV (Field of View) is the width of the view. The | | | | degrees and at 100 feet you can only see 19.2 |
| Vertical FOV (Field of View) is the height of the | | | | feet wide. This effectively makes the image a |
| view. The overall FOV is a combination of the | | | | "zoomed in" image. You are able then to capture |
| horizontal FOV and the vertical FOV. You can | | | | much more specific detail at 100 feet with longer |
| even measure it diagonally if you want too but its | | | | focal length lens like this. |
| really not necessary to do that. In addition to | | | | |