ZWO Duo-Band Filter


$99.00$179.00 $89.10$161.10

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Product Description

ZWO Duo-Band Filter is a dual narrowband filter primarily aimed at complementing our range of colour ASI cameras. The Duo-Band filter is aimed at the astronomer who may already own a One Shot Colour (OSC) camera and wants to image using narrowband techniques or emission objects without purchasing a mono camera, filter wheel and narrowband filter set.

The Duo-Band filter offers an economical entry into the world of narrowband imaging and can also offer a practical solution to imaging in light polluted urban areas.

The dual band pass nature of the Duo-Band filter passes light at Hα (656nm) and OIII (500nm) wavelength, and can reduce the interference from natural light sources such as moonlight, or artificial light pollution such as street lighting.

It can help improve the contrast and visibility of deep sky objects such as emission nebula using a OSC camera.

If you are looking for a solution to deep sky photography in light pollution area, then ZWO Duo-Band Filter will be a great choice.

The Duo-Band filter can be used with all ASI cameras and EFW Electronic Filter Wheel and comes in 1.25” and 2” sizes.



Technical Parameter

Name: ZWO Duo-Band Filter

Size: Standard 1.25” & 2”

Thickness: 1.85 mm

Bandwidth: HA (15nm) OIII (35nm)

Surface quality: 60/40 (Refer to MIL-O-13830)

Schott substrate material

More than 90% transmission at major OIII line 486.nm1, 496nm and 501nm.

More than 80% transmission at Ha line 656.3nm

ZWO-Duo-Band-filter (2)



Aerometal material. Precise CNC machining;

Fine sandblasting process and anodized finish;

Extinction treatment to prevent reflection;

Laser engraving font that will never fade;

Precise double-sided optical coating;

Fine-optically polished to ensure accurate 1/4 wavefront and <30 seconds parallelism over the both surfaces;




Kindly Reminder

The incoming light transmitted through the filter should be perpendicular to the filter, or the incident angle should be less than 8°. Therefore, this product is not suitable for wide-angle or ultra wide-angle lenses.



Test Results

Images captured with ASI color cameras and Duo-Band Filters. You can see that the potential for deep space photography in strong light polluted areas is vastly improved with the Duo-Band filters.

修改(3)(1)Heart(with without)-Duo-Filter(1)

修改(1)(2)Horsehead-(with without)-Filter(1)

Thanks to Tim Connolly’s Sharing


  • Fast Shipping(amount ≧ 299USD) for free
  • Fast Shipping(amount < 299USD) : $20.00
  • Free Shipping(amount < 299USD) (Air Mail, 3-4 weeks) (Free)

If you can’t get the air mail package after 4 weeks, please let us know ASAP:


  1. Fast Shipping: we will choose DHL, UPS, TNT, EMS etc to deliver it. Usually you will get your package in one week. We provide free fast shipping for order ≧ $299 or charge extra $20 for order < $299.
  2. Free Shipping: we will ship via DGM or China Post Registered Air Mail. It usually costs 2-3 weeks to reach US or Europe and costs 3-4 weeks to reach far places.
  3. Customers from Brazil and Chile should leave a message to provide your CPF or CNPJ as your custom needs it.
  4. Customers from Russia need to provide the name of your company.

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.
  • For customers who bought the camera from our dealer, dealer is responsible for the customer service for you.


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

  1. Avatar


    Would this work with the Celestron RASA 11? It’s at f/2.2 620mm focal length.


    • Avatar


      It may fail with fast ratio.


  2. Avatar


    You say it is not suitable for wide angle.
    My telescope is 360mm focal length, 60mm objective (F6.0).
    Is this too wide, or will this filter be suitable?
    Thank you


    • Avatar


      Yes it is suitable but you need to pay attention to your sensor size.


  3. Avatar


    “Duo band has 1.25 inch and 2 inch size, do you mean you want to know which size is suitable for your telescope?”

    Hello Katherine,
    thanks for your answer. My question was not about the size, I wanted to know if the filters are usable on such fast F-Ratios, like F1.9 in my case. Most narrowband filters fail under such conditions, as the passing wavelenghts shift because of the fast system. Will the filter pass the correct wavelenght even on F1.9 systems?
    Best regards and thanks a lot, Michael


    • Avatar


      Sorry It may fail.


  4. Avatar


    Is it suitable for Hyperstar systems (684mm / F1.9, C14 EHD)?


    • Avatar


      Duo band has 1.25 inch and 2 inch size, do you mean you want to know which size is suitable for your telescope?


  5. Avatar


    It is pass H-beta line?


    • Avatar


      Yes it is.



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