ZWO 1.25'' Ha SII OIII 7nm Narrowband Filter Set

ZWO 1.25" Ha SII OIII 7nm Narrowband Filter Set

Now: £352.00 (Save:  £40.00) Was:  £392.00
  (2 Reviews)
✓ 2 year warranty


2x in stock shipped 1-2 working days

Black Friday & Holiday Sale 2022 - Save 5-15% on many ZWO products.

Sale Ends Midnight, 3rd January 2023 subject to availability.

About this product

Model:  zwo_hso7_125
Part Number:  ZWO-HSO7-1.25SET

From 2018 onwards, ZWO upgraded their narrowband filters to reduce halos and improve overall performance. 

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

Ha 7nm

Has a bandwidth of 7nm and passes light at 656nm wavelength. 

OIII 7nm

Has a bandwidth of 7nm and passes light at 500nm wavelength. 

SII 7nm

Has a bandwidth of 7nm and passes light at 672nm wavelength.


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

Transmission Curve

Customer reviews

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Essential for DSO imaging
Wednesday, 1 September 2021  | 

High quality glass with no noticeable vignetting. Perfect range of narrowband for pulling out details in nebulae.

Rating (max 5):  
Tuesday, 24 September 2019  | 

Absolutely incredible difference in my pictures, I'm loving them!! High quality glass which you would expect for the price, but worth every penny. I'm looking forward to revisiting previous targets this winter, and adding some amazing details. The delivery was quick, and those tiny bits of glass were well protected with the packaging.


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