A method and apparatus for controlling coating material deposition on to a medical device. Images of material drops in flight are captured and an average single drop volume value is calculated by conversion of the captured drop images to a volume measurement. The average single drop volume value is used to calculate a total number of drops necessary to apply a desired amount of coating. Alternately, material is applied and the amount of material deposited is accumulated and adjustments are made to deposit only a desired amount of coating material. A drop volume is determined for either every drop or a sampling of drops as the drops are being applied. Adjustments to the coating process include changing drop size and changing a number of drops to be deposited.