ZWO 1.25" Duo Band Filter

  • Efficient and affordable narrowband imaging for color cameras.
  • Perfect for beginner narrowband imagers.
  • H-alpha Bandwidth: 15 nm.
  • OIII Bandwidth: 35 nm.
  • 1.25-inch Filter Size.


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  • Regular price $99.00

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ZWO 1.25" Duo Band Filter

The ZWO Duo Band Filters are designed to complement their large selection of color cameras. This dual-band filter is perfect for those astronomers who are already imaging using color cameras and don't want to transition to a monochrome camera set, requiring the addition of a filter wheel and narrowband set to complete the system. Be the efficient astronomer with ZWO's Duo Band Filters!

Efficient Color Camera Imaging

The ZWO Duo-Band filters are an excellent way for beginning astronomers to dive deep into the realm of narrowband imaging. Along with being focused on the H-alpha and OIII wavelengths, these filters are also a fantastic solution to dealing with light pollution that is becoming more and more prevalent. On top of this, the Duo-Band filters further improve the contrast and visibility of whichever deep-sky objects you're hoping to image using a color camera. Narrowband imaging doesn't get more convenient than this, especially at such impressive transmission rates of 80% (H-alpha) and 90% (OIII) for its two bandpasses.

ZWO Duo Band Filter Transmission Rates

Designed for Compatibility

Thanks to the design of these dual-band filters, essentially any camera or filter wheel that is compatible with 1.25-inch or 2-inch filters (depending on which size you purchase) can use these without a problem. The only real restraint, which is hardly a restraint to begin with when it comes to narrowband imaging, is that these are not suitable for wide-angle or ultra-wide-angle lenses because the incident angle should be less than 8 degrees for light passing through. For just about every night sky imager in the world, this will never be a problem.

Main Features of ZWO Duo-Band Filters

  • H-alpha Bandwidth: 15 nm.
  • OIII Bandwidth: 35 nm.
  • Made with Schott and Aerometal materials through CNC machining.
  • Extinction treatment to prevent reflection.
  • Dual bandpasses for convenient narrowband imaging.


Filter ShapeRound
Filter Thickness1.85mm
Filter TypeH Alpha
Filter TypeMultiband
Filter TypeOIII
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