A Hydrogen-beta telescope filter may be the only way to see the faint and elusive Horsehead, California, and Cocoon Nebulae. It blocks everything but the hydrogen-beta light these faint nebulas emit, providing the contrast needed for viewing
By isolating the Hydrogen-beta spectral line centered at 486.1 nm in a 12 nm band-pass and blocking other wavelengths, Orion's Hydrogen-beta Telescope Filter effectively blackens the background sky, allowing the faint nebula to become clearly defined. It increases contrast even under dark skies so you can visually capture these prized targets. Use with a moderate to large aperture telescope under clear, dark viewing conditions. Threaded to fit 1.25-inch telescope eyepieces and telescope diagonals.