The filter reduces irradiation, which is the distortion at the boundary between light and dark areas, such as along the lunar terminator. The Filter is especially useful to owners of large-aperture scopes, in which the Moon's brightness can be overwhelming. It uniformly reduces light over the entire visible spectrum. Screws into threaded eyepiece barrel. The 0.9 version has been measured to transmit 50% of the incident light. (Should technically be labeled as 0.3)

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The ND96 0.6 Astronomica Moon Filter reduces glare, allowing transmission of only a portion of the Moon's reflected light. Not only will you see more surface features, but you can study them in greater comfort.

The filter reduces irradiation, which is the distortion at the boundary between light and dark areas, such as along the lunar terminator. The Filter is especially useful to owners of large-aperture scopes, in which the Moon's brightness can be overwhelming. It uniformly reduces light over the entire visible spectrum. Screws into threaded eyepiece barrel.  The 0.6 version has been measured to transmit 25% of the incident light.