The ZWO Narrowband 7nm 1.25-inch Filter Set is designed for narrowband astrophotography, enhancing the contrast between nebulae and the night sky while mitigating the effects of light pollution. These filters are particularly useful for capturing detailed images of celestial objects by selectively passing light at specific wavelengths while blocking out unwanted light pollution.

This filter set includes three key filters:

Hydrogen-alpha (Ha) Filter: Passes light at 656.3nm with about 90% transmission, ideal for revealing fine details in emission nebulae.
Oxygen III (OIII) Filter: Passes light at 500.7nm with about 90% transmission, enhancing the contrast of planetary nebulae and some emission nebulae.
Sulphur II (SII) Filter: Passes light at 672.4nm with about 90% transmission, useful for highlighting regions rich in sulfur emission.
These filters feature a 7nm bandpass, suitable for most f/ ratios, and are designed to reduce the transmission of unwanted wavelengths, including artificial light from sources like mercury vapor and sodium vapor lamps, as well as natural skyglow. The filters have a fine-optically polished surface to ensure accurate 1/4 wavefront over both surfaces and a cut-off for infrared wavelengths from 700-1100nm, with less than 0.1% transmission of off-band light (OD3).

With a glass thickness of 2.0±0.03 mm and designed to fit 1.25" filter wheels or holders, this set provides essential tools for achieving high-contrast images in narrowband astrophotography. The "new" series features reduced internal reflections for improved imaging performance.

About ZWO Optical

Established in 2011, ZWO Optical is a fast-growing global astroimaging camera powerhouse based in Suzhou, China. Known for its iconic ZWO ASI 120MM Monochrome CMOS Camera, the first-ever planetary CMOS camera to beat a CCD in the early 2010s, ZWO has  pioneered new astroimaging technology with revolutionary new features, including USB 3,0, cooled systems, ADC and more. Today, ZWO Cameras is known by every passionate astrophotographer and is available in over 25 countries world-wide. 

Product Code: NB7nm1.25