The aperture photometry package "vaphot" was developed to perform reliable and precise time-series photometry of uncrowded fields. This package works within the Image Reduction and Analysis Facility (IRAF) environment and is built upon the standard aperture photometry task "phot" from IRAF. The design goal of vaphot was a simple-to-use photometry task with relatively few input parameters that performs precise aperture photometry using optimum-sized apertures. The derivation of optimum-sized apertures is outlined; the calculation of these sizes is performed by a subroutine "apcalc" within the vaphot package. We also outline the derivation of signal-to-noise (S/N) values for differential photometry, when the flux reference is constituted by an ensemble of reference stars. A comparison of vaphot against normal aperture photometry shows that the sizing of apertures with the point-spread function (PSF) of the charged coupled device (CCD) images mitigates the effects of changes in the size of the PSF during an observing run. The use of apertures sized individually to each star on the field does not greatly improve photometry compared to the use of similar-sized apertures. However, the use of photometry with previously determined optimum aperture sizes ensures that this photometry will be of the best quality that can be obtained.