ZWO Narrowband H-alpha Filter - 7nm

Narrowband filter does not eliminate the effects of light pollution or increase the object’s brightness. In many cases, they increase the contrast between nebula and night sky, not brightening the nebula.

It can reduce the transmission of certain wavelengths of light, specifically those produced by artificial light including mercury vapor, and both high and low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow).

Form 2018, ZWO Made a progress on narrowband filters with the new standard, provide better performance.

Technical Parameter:

Name: ZWO New narrowband 1.25″ filter

Size: 1.25″

Thickness: 5.5mm+2.5mm(thread)

Glass thickness: 1.85mm

Thread: M28.5*0.6 male thread

The ZWO narrowband O-III 7nm filter is designed for nebula observation allowing the 7nm bandwidth of light centered on a wavelength of 500nm through, which corresponds to OIII emission lines, blocking out all other light. Adding the ZWO O-III Narrowband filter to your imaging collection will help you go beyond the RGB imaging and will help capture your favorite nebulas in a totally new light, no matter how polluted your skies may be!

Technical Data

• FWHM：7±0.5nm
• Glass Thickness 2.0+/-0.03 mm (1.25”/31mm/36mm)
• Fine-optically polished to ensure accurate 1/4 wavefront over the both surfaces
• About 90% transmission at H-alpha line 656nm (H-Alpha filter )
• About 90% transmission at SII line 672nm (SII filter )
• About 90% transmission at major OIII line 500nm (OIII filter )
• Infrared wavelength 700-1100nm cut-off
• <0.1% transmission of off-band, OD3(Optical Density)

Transmission Curve

New Narrowband & Old Narrowband filter:

New OIII filter is based on the same base glass, new coating standard, better block rate of off-band.

Reviews

https://www.cloudynights.com/topic/627187-review-of-the-new-zwo-narrowband-filters-comparison-to-the-old-zwo-and-astrodon-filters/