ZWO 31mm SII 7 nm Filter
You will be amazed by your telescope’s astro-imaging capabilities with this 31 mm SII 7 nm Filter by ZWO! This filter allows you to take images that emulate those shot by the Hubble Space Telescope! All you have to do is couple the filter with an Oxygen III and Hydrogen-Alpha filter and you will be imaging like never before! Sulfur is in the deep red of the spectrum near 672 nm.
The ZWO SII 7nm 31mm Filter is unmounted. ZWO narrowband filters are fine-optically polished to reach an accuracy of 1/4 wave. Their performance is further enhanced by multiple layers of anti-reflection coatings.