Explore Scientific 2" 6.5nm S-II Nebula Filter

In addition to the turbulence in the air, the brightening of the night sky is the greatest obstacle to observing faint objects beyond the solar system. Street lights and other artificial lighting mean that the sky in human settlements is no longer properly black. As a result, the contrast and thus the perception of the deep-sky objects also suffer. Depending on the type of celestial object, however, part of the interfering light can be filtered out, making it easier to observe the objects.The Explore Scientific S-II filter uses the property of the so-called emission mist. These objects glow in certain colors, the so-called emission lines. The emission lines are linked to 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 only lets through the emission lines of the ionized sulfur at 672 nm. The effect is amazing: Suddenly, fog becomes visible in places that appear completely empty without a filter.When the sky is slightly brightened, there are many planetary nebulae, emission nebulae, and supernova remnants be seen completely problem-free when using this filter. A must for every amateur visual astronomer and also for astrophotography. The Explore Scientific mist filters are supplied with an individual test report - so you can be sure that you are receiving high-quality filters.