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Among these passbands, OIII emission overlaps on blue and green filters to achieve maximum transmission for high efficient imaging and natural colour result. Gap in between green and red filters serves the purpose to block out primary sodium (Na) line at 589 nm, often found in street lights causing light pollution, which also enhances colour balance and separation.
We care about delivering your filter in perfect form and thus every Optolong filter sits on a high density sponge carton lining and packaged in highly rigid plastic PP case with high pressure EVA case lining.
Optolong is a brand dedicated for astronomical filters R&D and production under Kunming Yulong Optical & Electronics Technology Co. Ltd. Yulong is a professional manufacturer of high quality filters since 1999. Yulong has passed ISO9001 quality certifcation and all products meet ROHS standard authorised by SGS test.
Their major equipment include ultra clean room, five precise vacuum coating machines, Shimadzu UV-VIS-NIR spectrophotometer, 12 sinks ultrasonic cleaning machines and grinding/rolling/cutting machines.
Optolong filters only use the best glass — German's Schott glass as the substrate which has an industry leading level of flatness which is crucial to minimise the occurence of halo and ensure high quality image.