Field emissions from a multiwalled carbon nanotube embedded in a conventional electropolished tungsten probe soften the tip of the tungsten by Joule heating, and the Coulomb attraction to the nanotube finery pulled from the tungsten tip resulted in an ultrasharp apex of the tungsten probe having a curvature of 5 nm radius. We also found that scanning transmission electron microscopy (STEM), when operated at low accelerating voltage, can visualize a local electric field at the probe apex. This local electric field, induced around the probe apex, deflected the primary electron beam of the STEM, producing a dark circular shadow surrounding the probe apex in the STEM image. The authors analyzed the distribution of this local field using a simple Rutherford scattering model. (C) 2007 American Vacuum Society.