ZWO Narrowband 7nm OIII,SII & Ha Filter Set - 1.25"

This Narrowband Filter Set from ZWO, also known as a SHO Set, is used for tri-color astrophotography to give you beautiful "Hubble" type results.  The three-piece filter set includes a 7 nm OIII, SII & Ha 1.25" threaded filter.  The glass thickness is 1.85 mm, and the overall thickness of the filter is 5.5 mm plus 2.5 mm for the M28.5 x 0.6 male threads.  Their 7 nm bandpass is designed for imaging nebulae.

H-Alpha (Ha) Filter

The ZWO H-Alpha filter has a bandpass of 7nm.  This Ha filter passes light at 656nm wavelength at a transmission rate of 80%. A narrowband H-alpha filter yields high-contrast images of nebulae, even when you're imaging in light-polluted skies, especially those plagued by mercury vapor & sodium vapor lights as well as skyglow caused by neutral oxygen emissions in the atmosphere.

Sulphur (SII) Filter

The ZWO SII Filter has a bandpass of 7 nm and passes light at 672nm wavelength at a transmission rate of 80%.  The SII filter is suitable for visual observation on most emission nebulae, planetary nebulae and supernova remnants, or use it with H-alpha and OIII narrowband filters (SHO Set) for tricolor CCD astrophotography.

Oxygen III (OIII) Filter

The ZWO OIII Filter is designed for nebula observation, allowing a 7nm bandwidth of light centered on a wavelength of 500nm to come through. Adding the ZWO OIII Narrowband Filter to your collection will help you go beyond RGB imaging and will help capture your favorite nebulae in a totally new light, no matter how polluted your skies may be!

Technical Details of ZWO Narrowband Filters

• 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)