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 (656.3nm) and OIII (500.7nm) 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”

Glass 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 495.9nm and 500.7nm.

More than 80% transmission at Ha line 656.3nm

Features

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.

Thanks to Tim Connolly’s Sharing