A method for correcting coaxial light image edge location errors in a precision machine vision inspection system is disclosed. The method comprises comparing an edge position measurement of a workpiece edge feature using coaxial light and stage light. Edge position measurements using stage light have a lower uncertainty than that of coaxial light. Position correction factors may be determined from the difference between the two edge position measurements. The position correction factors may be stored for correcting subsequent edge position measurements that are based on images acquired using coaxial light. In some embodiments, position correction factors may be determined based on comparing edge position measurements for a plurality of edges.