Alstar 2" Narrowband O-III Filter - Enhance Contrast in Dark Skies - Observe Clear Veil, Ring, Dumbbell and Orion Nebula, Among Many Other Objects

Each Alstar 2 inch O III Filter is individually inspected and proudly inscribed with the percentage of light transmittance of the two O III emission lines Not only useful at light polluted sites; the contrast is also increased at dark sky sites; can be used with all 2 inch eyepieces; Filter made from high grade glass with dichroic interference and antireflection coatings Completely blocks virtually all other visible wavelengths of light so views of nebulas are optimized; Increases contrast through selective filtration Anti reflection coated to prevent glaring and ghosting Especially useful for large aperture telescopes through which the light of the Moon can be extremely overwhelming; Allowing just for the Double Ionized Oxygen lines between 496 nm to 501 nm to pass through at 95 percent 2 inch O III Filter greatly enhances contrast during visual observation of gaseous and planetary nebulae in all sky conditions; The 2 inch filter allows high contrast imaging even in areas with strong light pollution