What is the FOV (field of view) of a camera?

[HerlySQR]

Hello, I'm making a system that includes setting a camera setup and restart the camera as how it was before, I'm including the field of view and saving it using:

prevCamera.fieldOfView = GetCameraField(CAMERA_FIELD_FIELD_OF_VIEW)

and to restart it I do:

SetCameraField(CAMERA_FIELD_FIELD_OF_VIEW, prevCamera.fieldOfView, 0)

But for some reason, when I do this, the camera zooms in further than it should instead of being the same as before, I wanna know why.