Abstract. A digital camera was used to measure diameters at various heights along the stem on 20 red oak trees. Diameter at breast height ranged from 16 to over 60 cm and height to a 10-cm top ranged from 12 to 20 m. The chi-square maximum anticipated error of geometric mean diameter estimates at the 95 percent confidence level were within ± 4 cm for all heights when obtained at a distance of 12 m or greater. Error increased with increased stem height from ± 3 to ± 7 cm for heights from 1 to 20 m. In general, the error is equivalent to 3 times the instrument precision, which varies with distance. Two-thirds of the volume estimates were within 8 percent of ‘actual’ volumes.