An adjustable support assembly for an object to be accurately positioned relative to a base, in particular for a secondary mirror of an optical mirror telescope, has at least one support structure connected to the base and to the object. The support structure has at least two struts extending in a non-parallel manner relative to each other, where each strut has associated therewith a drivable actuator element in such a way that the actuator element applies a force onto the strut that deflects the strut transversely to the longitudinal extension thereof. The support structure may be supported in an articulated manner relative to the base.