A sub-sampled deconvolution technique for crowded field photometry with theHST WFPC2 instrument was proposed by Butler (2000) and applied to search for opticalcounterparts to pulsars in globular clusters (Golden et al. 2001). Simulations showed thatthe method, which takes account of the point-spread function (PSF) spatial variation, canprovide better star detection and recovers the resolution lost to aberrations and poor sampling.The original emphasis was on precision photometry in crowded fields. In the presentwork, we have extended this technique to determine proper motions of stars in globularclusters. Actual HST images of the globular clusters, along with realistic simulations ofthe globular clusters, were used to benchmark the technique for astrometric accuracy. Theultimate aim is to use this dynamical data to search for intermediate-mass black holes inglobular cluster cores.