ZWO 31mm Ha 7nm Unmounted Narrowband Filter

ZWO 31mm Ha 7nm Unmounted Narrowband Filter

  (1 Review)
✓ 2 year warranty


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About this product

Model:  zwo_ha_31-7nm
Part Number:  ZWO-Ha7nmD31

New & Improved with higher light transmission and less reflection (reduced halos around bright stars). 

The ZWO H-Alpha filter has a bandpass of  7nm and passes light at 656nm wavelength. Light transmission peaks at around 90%. 

Providers high-contrast images with rich detail of nebula, even in areas with strong light pollution! 


  • FWHM: 7±0.5nm
  • Glass Thickness 2.0+/-0.03 mm (1.25”/31mm/36mm)
  • Fine optically polished glass ensures accurate 1/4 wavefront over both surfaces
  • Around 90% transmission at H-alpha line 656nm
  • Infrared wavelength 700-1100nm cut-off
  • <0.1% transmission of off-band, OD3 (Optical Density)

Transmission Curve

Customer reviews

Average Rating (1 Review):  
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Works as it should and seems par-focal with my other ZWO filters.
Monday, 18 February 2019  | 

Great for picking out nebula in galaxies. The cone nebula looked well defined, when nothing was showing in R,G, or B.( bright moon)


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