Abstract: A line of sight target adaptor to be used with theodolite and photogrammetric optical targets involves a base portion in the shape of a segment of a sphere provided with a cylindrical portion upstanding from the side of the segment from the flat portion of the interior portion of the segment having a centrally disposed coaxial cylinder to receive a target positioned therein, the target being so dimensioned that it will be concentric with the center of a sphere based on the dimensions of the segment of the sphere constituting the base portion of the target adaptor.