EXPLORE SCIENTIFIC 1.25" S-II Nebula Filter 12nm (Refurbished)

One of the most important obstacles for the exploration of the night sky is the brightening of the night sky by artificial lights, such as streetlights. The night sky is not really dark in the vicinity of towns or cities, which reduces the visibility of objects beyond the solar system enormously. Depending on the type of celestial object, it is possible to increase the contrast dramatically by blocking the interfering artificial light. The EXPLORE SCIENTIFIC S-II filter uses the property of the so-called emission nebulae. These objects glow in certain colors, the so-called emission lines. The emission lines are associated with certain chemical elements - in this case ionized sulfur. The EXPLORE SCIENTIFIC S-II nebula filter blocks all other colors (and thus almost all artificial light) and lets only the emission lines of ionized sulfur at 672 nm through. The effect is amazing: suddenly, nebulae become visible in places that appear completely empty without the filter. In slightly brightened skies many planetary nebulae, emission nebulae and supernova remnants can be seen without any difficulties when using this filter. A must for every visual observer and for astrophotography. EXPLORE SCIENTIFIC nebula filters come with an individual test report - so you can be sure to get high quality filters. FEATURES Simplifies the observation of planetary nebulae, emission nebulae and supernova remnants Blocks almost all artificial light Lets only the emission lines of ionized sulfur at 672 nm pass Transmission bandwidth: 12 nm Allows for more contrast in faint deep sky objects Ideal for use near cities, in slightly brightened skies Individual test certificate included to guarantee you receive a premium filter SCOPE OF DELIVERY 1x 1.25'' S-II nebula filter