Horizontal Cross Hair Should Lie in a Plane Perpendicular to the Vertical axis |
Test A well-defined point is focused along the horizontal cross hair on one side of the field of view. The instrument (telescope) is then rotated about its vertical axis. If the point appears to travel along the horizontal cross-hair, the instrument is in adjustment i.e., the horizontal cross-hair lies in a plane perpendicular to the Vertical axis. Otherwise, there is a need for adjustment. |