Abstract
A study was undertaken to statistically compare equivalent area field counts and dust concentrations obtained by using a microprojector and a light-field microscope. This was to test the opinion that the two methods, although allowed by the standard dust counting technique, are not comparable. The precision between observers and within one method was also examined. The study shows that the two counting methods do not produce comparable results and that, on the average, higher dust concentrations can be expected with the microprojector.