A comparison optical system (1) comprising several image-acquiring optical subsystems is disclosed. A bridge (3) mechanically and optically connects the optical subsystems to one another. Each of the image-acquiring optical subsystems possesses an XYZ stage (8a, 8b), movable in motorized fashion, on which a sample to be examined is placed. Also provided is a control unit which moves the XYZ stages (8a, 8b), movable in motorized fashion, synchronously in all three spatial directions. The synchronous motion of the XYZ stages (8a, 8b) can be switched on and off by the user.