ZWO New narrowband 1.25″ filter


Available now! ; )

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Product Description

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).

Form 2018, ZWO Made a progress on narrowband filters with the new standard, provide better performance.

Technical Parameter:

Name: ZWO New narrowband 1.25″ filter

Size: 1.25″

Thickness: 5.5mm+2.5mm(thread)

Glass thickness: 1.85mm

Thread: M28.5*0.6 male thread

The ZWO H-Alpha filter has a bandpass of  7nm and passes light at 656nm  wavelength, light transmission rate comes up to 80%. Best choice of narrowband H-alpha astrophotography filter for high-contrast imaging and revealing rich details of the nebula even in areas with strong light pollution, just prepare to experience the infinite fun with it!



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.



The ZWO narrowband O-III 7nm filter is designed for nebula observation allowing the 7nm bandwidth of light centered on a wavelength of 500nm through,  which corresponds to OIII emission lines, blocking out all other light.  Adding the ZWO O-III Narrowband filter to your imaging collection will help you go beyond the RGB imaging and will help capture your favorite nebulas in a totally new light, no matter how polluted your skies may be!


Technical Data

  • FWHM:7±0.5nm
  • Glass Thickness 2.0+/-0.03 mm  (1.25”/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

NB filters TP

New Narrowband & Old Narrowband filter:

New Ha filter is based on the new base glass, less reflection( less halo of bright stars).


New SII filter is based on the new base glass, less reflection( less halo of bright stars).


New OIII filter is based on the same base glass, new coating standard, better block rate of off-band.


We made a test of our Ha Filters (ASI1600 mono camera, single frame, 300s, DDP in MaximDL) :

real test of Ha



It will take around 60-90 days for shipment via ePacket/China Post Registered Air Mail/EMS, which can’t be guaranteed due to force majeure.

  • Fast Shipping(amount ≧ 199USD) for free
  • Fast Shipping(amount < 199USD) : $20.00 (We do not provide free shipping from now on.)

If you can’t get the air mail package after 2months, please let us know ASAP:


  1. Fast Shipping: we will choose DHL, UPS, FedEx etc to deliver it. Usually you will get your package within one month.
  2. Customers from Brazil and Chile should leave a message to provide your CPF or CNPJ as your custom needs it.
  3. Customers from Russia need to provide the complete English name with three words as well as the English shipping address.

Tracking site


China air mail:



  • The price list on our website is USD without tax.
  • Please note that buyers are liable to pay tax involved, such as Import tax, VAT , customs handling fee, etc. The additional fees may be collected at time of delivery by courier.
  • For best local service we advise customers buy our cameras form local dealers.

Warranty and Return Policy

  • We provide 2-year warranty for our products, we will offer the repair service for free within warranty period. After the warranty period, we will continue to provide repair support and service on a charged basis. We do not provide any replacement unless ZWO confirmed the product is DOA (Dead On Arrival).
  • This warranty does not apply to damage that occurred as a result of abuse or misuse, or caused by a fall or any other transportation failures after purchase.
  • Customer must pay for shipping when shipping the camera back for repair or replacement. If we confirm you can get a replacement, goods must be returned with all accessories, instructions, etc and must be suitably packed.
  • If you get a faulty camera, please contact us as soon as possible though email: Please describe the problem in detail and we will do our best to help you solve the problem. Most instances perceived problems are simply bad driver install or software configuration.
  • We will provide you RMA number if your camera requires warranty repair. We refuse any return without RMA number!
  • For customers who bought the camera from our dealer, dealer is responsible for the customer service for you.

Before first usage of this product read manuals and install correct drivers and software.

Do you have question, answer or comment? Post here!

  1. Avatar


    Is there any plans to change the glass for the OIII filter like you did for the Ha and SII? If not, why not? The reviews show significant improvement in the Ha and SII filters, but the OIII filter is still causing issues with artifacts and halos. See the very review that you reference on this site. Seems like you are so close to having good filter set but for some unknown reason quit before completing the set.


    • Avatar


      OIII filter is quite different, glass base of HA and SII can not make OIII wave length pass it. So the halo will be more obvious than Ha and SII, even we already use higher standard to produce OIII filter.
      We still in R&D to figure out how to make it better, I’m sure in the further we could make a perfect set of narrowband filters.


  2. Avatar


    I have a new ASI294 Pro Colour camera. Interested in a H Alpha filter to enhance Nebula like Orion and Carina …red Nebula. Does that mean the filter will block the Debayer Green and Blue meaning I will get only every 4th red cell ? Also would it be best to position the filter before the ASI294 but after the Off Axis Guider as there would be stars lost from view?


    • Avatar


      Yes. The Ha filter will block the green and red light, so it would be the best to put the OAG in the front.


  3. Avatar


    I just received a filter OIII but I can not see if it’s the new or the old model. How to see the difference ???


    • Avatar


      Depand on your purchase time, if recently, it must be the new one.


  4. Avatar


    I received a set of Narrowband with my ASI1600 kit purchase about a yr ago. Is it possible to get credit for that and update without full costs of new set?


    • Avatar


      Sorry, filters are not support upagrade service.


  5. Avatar


    Why does the filter side direction (to telescope vs. to detector) matter ?


    • Avatar


      Yes, because the coating of two sides is different, wrong side face to telescope will cause more refection problem, such as halos.



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