Astrodon 3 nm Narrowband Filters - SII filter, 50mm SII3_50R-200152 (2nd Quality)
This individually serialized filter, SII3_50R-200152, has been scored at 9.8 and has a 14.38% discount. Astrodon 2nd Quality filters are still covered by our warranty for longevity, but are otherwise sold "as is" and are not returnable.
Astrodon 3 nm Narrowband Filters - SII filter
If you want the look of Hubble Space Telescope (HST) images, such as the famous “Pillars of Creation” (the Eagle Nebula, Messier 16), then the next filter to consider adding to your collection after H-a and OIII is the SII (es-two) or sulfur filter. The SII filter, like H-a, is a deep red filter near 672 nm. H-a, OIII and SII filters provide that Hubble look for many emission nebulae. Again, tri-color narrowband imaging with these three filters can be done with the moon up, so your equipment is not sitting dormant for several weeks.
Astrodon SII filters have a center bandwidth of 671.6nm