The Celestron Moon Filter is an inexpensive telescope eyepiece filter for reducing the brightness of the moon and improving contrast, so greater detail can be observed on the lunar surface.
The clear aperture is 21mm and the transmission is about 18% which makes this filter well suited for practically any aperture telescope making viewing the Moon far easier on the eye and helping preserve dark adaption.
This filter simply threads into the standard filter thread of 1.25" eyepieces and accessories.
The Moon thanks to it's brightness is probably the easiest of all celestial objects to both observe and photograph.The addition of a filter will enhance your viewing pleasure no end.
The Moon's gravitational influence produces the ocean tides and the minute lengthening of the day.
The current orbital distance is about thirty times the diameter of the Earth, which causes it to be the same size in the sky as the Sun-allowing the Moon to cover the Sun precisely in total solar eclipses.