FOV (Field of View)

The so-called FOV (Field of View) is the extent that a camera or an optical instrument can record of its surroundings.

In the human eye, the eyelids, eyelids, etc., limit the facial field, and the opening can be specified with fixed angles (horizontal and vertical). Anything outside this FOV is not detected.

The specification in degrees is useful, because of the variable metric size of the FOV, depending on the focal length. For example, one speaks of a Field of View of 20 ° x 16 ° (horizontal x vertical). The FOV is inversely proportional to the focal length f, where x is the diagonal of the sensor:

 FOV = 2 arctan (x/ (2f))


fov camera

FOV of a thermal imaging camera

The FOV also plays an important role in thermal imaging cameras. Devices with small FOVs tend to be better for small objects and large distances. It is necessary to consider the application areas before the purchase and to pay attention to the minimum distance of the thermal imaging camera.

If a window is to be examined in a small room with a thermal imaging camera, for example, you can not always go arbitrarily far away from the window (bath windows, basement windows, etc.). Then a camera with a large FOV is better, since it can be better operated in conditions with a lack of space. Heating and electrical installations are also often deployed in small rooms where free movement is limited.

On the other hand, with a small FOV smaller objects can be better captured. At the same minimum distance to the object, a smaller object is better resolved (if it is detected completely). With a large FOV you would also capture things outside the object being examined, thus “wasting” pixels.

If you have sufficient freedom of movement and are able to maintain the minimum distance to the object, you can of course achieve your measurement goal with both a large and a small FOV. It is also the minimum distance to the object, which should be considered before purchasing a thermal imaging camera in connection with the FOV. The price of a thermal imaging camera plays no role here and is independent of the FOV.