Abstract: A jig for mounting one or more lenses on a two axes coordinate movement bed of a CNC machine for machining the one or more lenses. The jig comprises a carriage (29) having one or more lens holders (36) for holding one or more lenses (13, 14), each lens having a mounting block (19) bonded to a convex surface of the lens (43). The carriage (29) is rotatable about a first axis so as to be able to present one or more lenses (13, 14) to a tool of the machine where it is desired to machine the one or more lenses (13, 14). The lens is constrained to restrict rotation of the one or more lenses about an axis normal to the concave (42) and/or convex (43) surfaces of the one or more lenses (13, 14).