ZWO narrowband 31 mm (unmounted) NB7nm set of three filters (HSO, SKU: ZWO NB7nmD31)

ZWO, a leading company catering to professional astrophotographers, has recently unveiled an upgraded version of narrowband filters designed specifically for capturing stunning images in the HSO color palette.

The key highlight of this filter kit is its exceptional performance, featuring high transmission and an incredibly narrow half-bandwidth of just 7 nm. Manufactured on a 2 mm thick glass substrate, each filter in the kit is coated with a comprehensive multilayer coating to optimize its functionality.

Typically, narrowband filters aim to enhance the contrast between celestial objects and the sky's background rather than eliminating light pollution. However, ZWO's latest filters allow astrophotographers to observe and capture colorful images of nebulae, including emission, planetary, and remnants of supernova explosions, even in environments with severe light pollution.

It is important to note that for Hα and SII filters, their correct orientation is crucial. The side with the purple coating should be facing the camcorder or camera.

Key Features of ZWO HSO 31 mm Narrowband Filters:

A set of three filters tailored for astrophotography in the HSO (HST) palette, ensuring maximum transmission of approximately 90%.

Half-bandwidth of 7 nm, enabling precise isolation of specific wavelengths.

Filters coated with a complete multilayer coating to eliminate the halo effect commonly observed around stars.

Technical Specifications:

• Filter type: Rimless narrowband filter.
• Filter diameter: 31 mm.
• Filter thickness: 2.0 ± 0.03 mm.
• Half-bandwidth (FWHM): 7 nm.
• Maximum transmission for the 656 nm (Hα) line: Approximately 90%.
• Maximum transmission for the 672 nm (SII) line: Approximately 90%.
• Maximum transmission for the 500 nm (OIII) line: Approximately 90%.
• Infrared (IR) blocking range: 700 - 1100 nm.
• Out-of-band transmission: Less than 0.1%.
• Equivalent optical density for the blocked range: OD3.
• Coating type: Full multilayer coating (FMC).

Components of the Kit:

The ZWO HSO 31 mm Narrowband Filters kit comprises the following:

• ZWO Hα 7 nm filter.
• ZWO SII 7 nm filter.
• ZWO OIII 7 nm filter.
• Protective plastic boxes for each filter.

Astrophotographers can now leverage the advanced capabilities of ZWO's HSO 31 mm Narrowband Filters to capture breathtaking images of nebulae, even in challenging lighting conditions. These filters, with their superior performance and precision, open up new opportunities for capturing the beauty of the cosmos.