code: def fov(self):
          
          if self._fov is None:
              fov = [2.0 * np.degrees(np.arctan((px / 2.0) / f))
                     for px, f in zip(self._resolution, self._focal)]
              fov = np.asanyarray(fov, dtype=np.float64)
              self._fov = fov
          return self._fov
docs: Get the field of view in degrees.
  
          Returns
          -------------
          fov : (2,) float
            XY field of view in degrees