ZWO HA 7NM FILTER 1.25"

Narrowband filters do not eliminate the effects of light pollution or increase the object’s brightness, but rather increase the contrast between nebula and night sky. 

They 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).

Technical Parameters:

Name: ZWO New narrowband 1.25″ filter

Size: 1.25″

Thickness: 5.5mm+3.5mm (thread)

Thread: M28.5*0.6 male thread

The ZWO H-Alpha filter has a bandpass of 7nm and passes light at 656nm wavelength, light transmission rate comes up to 80%. 

After putting the filters into EFW, must sure that correct side of narrowband filters face to telescope and camera.

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 )
• Infrared wavelength 700-1100nm cut-off
• <0.1% transmission of off-band, OD3(Optical Density)

Transmission Curve