The properties of both insulators and metals can be characterized capacitively with scanning probe microscopy, though the techniques employed are different. Intermittent contact scanning capacitance microscopy (IC-SCM) is a useful technique for characterizing the dielectric constant of insulators. Scanning Kelvin force microscopy (SKFM) can image potential distributions and work functions within conductors. Both techniques depend on the capacitance between the tip and sample, which has an inverse square dependence on tip-sample separation, limiting spatial resolution. A differential data acquisition technique to improve spatial resolution is described.