Abstract: In a scanning electron microscope of the type including a manually controllable stigmator coil system for compensating for beam astigmatism, means are included for providing, simultaneously and in a single image, a mapped display of all possible stigmator correction values as a function of coordinate location in the display. The operator of the microscope, by viewing the mapped display, may readily locate the best-corrected area therein and thereby select the correction values that best achieve astigmatism correction. Means are also included which enable the operator to locate the best-corrected area on the mapped display by movable index markers which automatically couple the proper correction values to the stigmator system. The mapped display also serves as an aid in obtaining optimum beam focus and as an indicator of the condition of the microscope.