Explore Scientific 2″ ND 0.9 Filter
Explore Scientific’s 2″ Neutral Density (ND) Filter allows light to pass uniformly across the whole visual spectrum. This makes it a superb filter for reducing glare and irradiation when observing the Moon with any telescope 4″(10.2cm) and larger.
The Explore ND Filter has a density of 0.9 and a transmission of 13% and comes in a 2″ metal cell that can be threaded easily onto the 2″ barrel of an eyepiece, Barlow, or another accessory. Besides working great on the Moon, it will help split close double stars where one star is much brighter than the other. Neutral density filters also help decrease brightness when using your telescope for terrestrial viewing on a bright, sunny day.