Astronomy Specialist



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The ZWO Duo-band is a narrowband filter ideal for emission and planetary nebulae. Its special coatings allow the transmission of OIII and H-Alpha wavelengths whilst blocking all other wavelengths. This allows to enhance the contrast of nebulae reducing the effect of the light pollution, natural skyglow and moonlight. 

This filter is particularly suitable for colour cameras. In fact, the narrowband filters (OIII, H-Alpha, H-Beta, SII) have a bandpass of only 7-8 nm allowing the transmission of  selected area of the spectrum thus producing monochromatic images. The ZWO Duo Band has a bandwidth of 15nm in Hα and 35nm in OIII allowing to produce colour images with OSC cameras. 

These filters can be used with the ZWO filter wheels. 



The incident light to the filter should be within an angle of 8°. Therefore, this product is not suitable for wide-angle or ultra wide-angle lenses.


    Glass thickness

    1.85 mm

    Optical flatness

    1/4 λ (wavefront)

    Bandpass transmission

    Above 90% for OIII, over 80%for Hα


    1.25" or 2"

    Filter material

    Schott substrate

    Surface quality

    60/40 scratch/dig


    ZWO-DB1.25 (for 1.25" filter),  ZWO-DB2 (for 2" filter)





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