ZWO OIII 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, 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 narrowband O-III 7nm filter is designed for nebula observation allowing 7nm bandwidth of light centered on a wavelength of 500nm through, which corresponds to OIII emission lines, blocking out all other light. 

After putting the filters into the EFW, ensure that the correct side of narrowband filters are facing the 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 major OIII line 500nm (OIII filter )
• Infrared wavelength 700-1100nm cut-off
• <0.1% transmission of off-band, OD3 (Optical Density)

Transmission Curve

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