The 2" 12nm S-II nebula filter from Explore Scientific is designed to enhance the observation of deep-sky objects, such as planetary nebulae, emission nebulae, and supernova remnants. By blocking almost all artificial light and only allowing the emission line of ionized sulfur at 672 nm to pass through, this filter reveals hidden details and improves contrast, even under a partially lit sky. With a bandwidth of 12 nm, it is ideal for amateur astronomers and astrophotographers seeking to observe faint celestial objects in urban conditions. Each filter comes with an individual test certificate to ensure its high quality.