Busch Millux 6x30

This Millux has an unusual system of collimation, consisting of the use of 8 screws (2 for each of the 4 prisms), located on the housing and aligned in pairs with the hypotenuse of each prism to displace these in opposite directions. Thus, when advancing one of the screws this pushes the prism in a direction transverse to the optical axis and therefore, the antagonistic screw has to go back. In this way, each prism can be shifted as necessary to achieve the final alignment of the instrument. The pressure exerted by the screws on the edges of the prisms is done through special metal pieces that protect the prisms from possible fractures (typically, chipped at the edge of the prism). This collimation system is superior to that used in most current mid-range binoculars, consisting of 4 screws to tilt the prisms.