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Grey filter with 13% passage. Who would like to observe the moon with large telescopes, usually needs a relativley dark moon filter, so that also a sufficient absorption is present with very large openings also. This filter is recommended thereby starting from a diameter of 200mm. Who thus with 250mm or 300mm observed is particularly recommended this filter. Observers, in addition, who can to observe take the somewhat brighter filter ND 25 with 200mm.
The optical quality is very good. The glass is plan-parallel and also at the edge has one still another perfect moon picture and must not with distortions be annoyed.
