Arcturus OIII Nebula Filter 1.25
The Arcturus OIII Nebula Filter uses the very latest in optical filtering techniques to produce a fine light pollution filter. The filter element is a material that has its passband precisely controlled through excitation by a laser. The material is then laser-cut and placed into a filter holder, resulting in a filter that blocks light at wavelengths typically found in outdoor lighting systems. The Arcturus OIII Nebula Filter makes a fine light pollution filter that passes a very high percentage of light originating from stellar sources. The filter is threaded to accept another filter or other accessory. Attached to an eyepiece, the fllter protrudes an additional 5/16" (7.2mm) beyond the end of the barrel.