def moveCamera(self, camstart, camstop, fraction):
        """
        Takes as input two ``vtkCamera`` objects and returns a
        new ``vtkCamera`` that is at an intermediate position:

        fraction=0 -> camstart,  fraction=1 -> camstop.

        Press ``shift-C`` key in interactive mode to dump a python snipplet
        of parameters for the current camera view.
        """
        if isinstance(fraction, int):
            colors.printc("~lightning Warning in moveCamera(): fraction should not be an integer", c=1)
        if fraction > 1:
            colors.printc("~lightning Warning in moveCamera(): fraction is > 1", c=1)
        cam = vtk.vtkCamera()
        cam.DeepCopy(camstart)
        p1 = numpy.array(camstart.GetPosition())
        f1 = numpy.array(camstart.GetFocalPoint())
        v1 = numpy.array(camstart.GetViewUp())
        c1 = numpy.array(camstart.GetClippingRange())
        s1 = camstart.GetDistance()

        p2 = numpy.array(camstop.GetPosition())
        f2 = numpy.array(camstop.GetFocalPoint())
        v2 = numpy.array(camstop.GetViewUp())
        c2 = numpy.array(camstop.GetClippingRange())
        s2 = camstop.GetDistance()
        cam.SetPosition(p2 * fraction + p1 * (1 - fraction))
        cam.SetFocalPoint(f2 * fraction + f1 * (1 - fraction))
        cam.SetViewUp(v2 * fraction + v1 * (1 - fraction))
        cam.SetDistance(s2 * fraction + s1 * (1 - fraction))
        cam.SetClippingRange(c2 * fraction + c1 * (1 - fraction))
        self.camera = cam
        save_int = self.interactive
        self.show(resetcam=0, interactive=0)
        self.interactive = save_int
Takes as input two ``vtkCamera`` objects and returns a
        new ``vtkCamera`` that is at an intermediate position:

        fraction=0 -> camstart,  fraction=1 -> camstop.

        Press ``shift-C`` key in interactive mode to dump a python snipplet
        of parameters for the current camera view.