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ZWO Duo Band Filter

In Stock - Ships Today if Ordered by 3pm! (Tues - Fri)

FedEx Ground Order Cutoff is 11am


We will price-match Canadian astronomy dealer pricing


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ZWO Duo Band Filters are dual narrowband filters primarily aimed at complementing the range of one-shot colour cameras including ZWO's ASI cameras. They're perfect for the astronomer who may already own a One Shot Colour (OSC) camera and wants to image using narrowband techniques on emission objects without purchasing a mono camera, filter wheel and narrowband filter set.

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

Contrast and visibility of deep sky objects such as emission nebulae is improved.

If you're looking for an economical solution to deep sky photography in light polluted areas ($139 for 1.25" and $249 for 2"), the ZWO Duo Band Filters are a great choice.

The 1.85 mm Duo-Band filter can be used with most cameras and filter wheels, including ASI cameras and EFW Electronic Filter Wheels, and comes in 1.25” and 2” sizes.



Technical Parameters

Sizes: Standard 1.25” & 2”

Thickness: 1.85 mm

Bandwidth: HA (15 nm) OIII (35 nm)

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

Schott substrate material

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

More than 80% transmission at Ha line 656.3 nm

ZWO-Duo-Band-filter (2)



Aircraft grade aluminum with precise CNC machining

Fine sandblasting processing 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




Note on Wide Angle Applications

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.


Returns Policy

You may return most new, unopened items within 30 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

Items that have been opened, damaged or are otherwise unsaleable will be subject to a minimum 10% restocking fee, to be assessed by Telescopes Canada upon receipt of the returned goods

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the 'Complete Orders' link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.


We can ship to virtually any address in the world. Note that there are restrictions on some products, and some products cannot be shipped to international destinations.

When you place an order, we will estimate shipping and delivery dates for you based on the availability of your items and the shipping options you choose. Depending on the shipping provider you choose, shipping date estimates may appear on the shipping quotes page.

Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.

Typographical Errors and Order Cancellations

Telescopes Canada reserves the right to cancel an order due to an error in pricing by Telescopes Canada or one of our suppliers, equipment being no longer obtainable, or other events which are out of our control.

Client-Initiated Cancellations

Client-initiated order cancellations are accepted prior to delivery of the equipment to the customer, thereafter it is a return.

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