An optical filter is formed of a layer stack that includes metallic layers and dielectric layers, with at least one dielectric layer being defined by more than one zinc-based film. These zinc-based films have different percentages of zinc. The selections of the percentages are based upon the positions of the films within the dielectric layer. An unexpectedly low sheet resistance is available if the zinc-based film that immediately precedes forming a metallic layer has a percentage of zinc in the range of 80 percent to next to 100 percent. Process stabilization and manufacturing cost are provided by placing the percentage of the lower zinc-based film closer to 50 percent (25-75). Process stabilization is further enhanced by providing an indium-based film within the dielectric layer adjacent to the metallic layer.