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Narrowband filter does not eliminate the effects of light pollution or increase the object’s brightness. In many cases, they increase the contrast between nebula and night sky, not brightening the nebula.

It can reduce the transmission of certain wavelengths of light, specifically, those produced by artificial light including mercury vapor, and both high and low-pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow).

From 2018, ZWO Made progress on narrowband filters with the new standard, providing better performance.

The ZWO narrowband S-II 7nm filter passes light at 672nm wavelength with a bandpass of 7nm which is designed for nebula observation. It is suitable for visual observation on most emission nebulae, planetary nebulae and supernova remnants, use it with H-alpha and OIII narrowband filters (SHO Set) for tricolor CCD astrophotography.

New narrowband 1.25″ filter

Technical Parameter

Size: 1.25″

Thickness: 5.5mm+2.5mm(thread)

Glass thickness: 1.85mm

Thread: M28.5*0.6 male thread

ZWO New narrowband 31mm filter

Technical Parameter

Size: D=31mm

Thickness: 2mm

The ZWO narrowband S-II 7nm filter passes light at 672nm wavelength with a bandpass of 7nm which is designed for nebula observation. It is suitable for visual observation on most emission nebulae, planetary nebulae and supernova remnants, use it with H-alpha and OIII narrowband filters (SHO Set) for tricolor CCD astrophotography.

ZWO New narrowband 2″ filter

Technical Parameter

Name: ZWO New narrowband 2″ filter

Size: 2″

Thickness: 5mm+2.5mm(thread)

Glass thickness: 1.85mm

Thread: M48*0.75 male thread

ZWO New narrowband 36mm filter

Technical Parameter

Name: ZWO New narrowband 36mm filter

Size: D=36mm

Thickness: 2mm

The ZWO narrowband S-II 7nm filter passes light at 672nm wavelength with a bandpass of 7nm which is designed for nebula observation. It is suitable for visual observation on most emission nebulae, planetary nebulae and supernova remnants, use it with H-alpha and OIII narrowband filters (SHO Set) for tricolor CCD astrophotography.

• Hubble look of images can be made by the combination of H-alpha, OIII-CCD and SII-CCD, such as the famous “Pillars of Creation” (M16 Eagle Nebula)
• Narrowband imaging with SHO set (H-alpha, OIII-CCD and SII-CCD) can be done with the moon up in heavy light pollution, so your equipment is not sitting dormant for several weeks
• H-alpha filter is the first narrowband addition to LRGB set for most imagers who blend a black-and-white Ha image into RGB data to enhance structural detail while maintaining natural look

Technical Data

• FWHM：7±0.5nm
• Glass Thickness 2.0+/-0.03 mm (31mm/36mm)
• Fine-optically polished to ensure accurate 1/4 wavefront over the both surfaces
• About 90% transmission at H-alpha line 656nm (H-Alpha filter )
• About 90% transmission at SII line 672nm (SII filter )
• About 90% transmission at major OIII line 500nm (OIII filter )
• Infrared wavelength 700-1100nm cut-off
• <0.1% transmission of off-band, OD3(Optical Density)

Transmission Curve