  A class of observers is introduced that interpolate smoothly between the
Schwarzschild observer, stable at spatial infinity, and the Kerr-Schild
observer, who falls into a black hole. For these observers the passing of the
event and inner horizon takes a finite time, which diverges logarithmically
when the interpolation parameter $\sigma$ goes to zero. In the field theoretic
approach to gravitation, the behavior at the horizons becomes regular, making
the mass of the metric well defined.
