Optolong narrowband filters boost the contrast of emission nebulae and supernova remnants for professional results, even under a bright sky affected by light pollution. Each filters cut out ultraviolet and infrared light so there is no need to use an IR-cut filter.
Optolong filters are made with multi-coated optical glass. The interferential coating is deposited on the substrate using electron-beam gun evaporation with ion-assisted deposition coating technology. This increases the filter durability and resistance to scratching, as well as stability of the CWL (central wavelength). The planetary rotation system offers precision and homogeneity of the coatings ensuring high transmission of the pass-band and high optical density off-band.