The Explore Scientific H-Alpha 1.25" 12nm filter is an essential tool for astrophotographers looking to capture emission nebulae, even under skies polluted by artificial light. This filter blocks almost all other colors, allowing only the red hydrogen emission line to pass through. It effectively eliminates disruptive light from mercury and sodium vapor lamps, revealing details that are invisible to the naked eye. With a bandwidth of 12nm, this filter enhances the contrast and sharpness of deep-sky objects, enabling the photographing of nebulae that appear invisible without a filter. Ideal for astrophotographers in urban settings, it ensures surprisingly high-quality results despite light pollution. Each filter comes with an individual test certificate to guarantee its high quality.