ZWO Narrowband Filter Set with 31mm OIII, SII, and H-Alpha Filters
All of the 31mm filters in this ZWO Narrowband Filter Set are unmounted. These 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.
ZWO 31mm Unmounted OIII Filter
OIII, or doubly ionized oxygen, emits light in the blue/green, or teal portion of the spectrum near 500 nm. Planetary nebulae and supernova remnants emit most of their light in the OIII line.
ZWO 31mm Unmounted Ha Filter
Hydrogen-Alpha is the most dominant emission line in star-forming regions. H-Alpha light is created by atomic hydrogen, and is responsible for the red color seen in most nebulae.
ZWO 31mm Unmounted SII Filter
Sulfur is in the deep red of the spectrum near 672 nm. When combined with H-a and OIII, these three filters will produce images with colors that are reminiscent of those taken by the Hubble Space Telescope.
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