These high quality anodized aluminium, optical glass variable polarising filters reduce the amount of light entering your eyepiece. You can progressively dim the view when observing a bright object, such as the Moon or certain planets
This 1.25in filter consists of two joined polarized filters that provide continuously from about 2% to 40% as the rotating filter is adjusted. Great for lunar viewing without ruining your dark adaptation from staring at a bright image.
For glare-reduction in observing the Moon the #905 Variable Polarizer includes two Polarizer filters mounted in a specially-machined cell. The #905 permits variable settings of the light transmission between 5% and 25%, to account for varying lunar surface brightness