6.5nm OIII Narrow Band Filter

This filter is an additional 6.5 nm narrowband OIII designed for nebula observation with a 500 nm centered wave that matches the OIII emission lines and reduces the transmission of certain wavelengths of light, especially those produced by artificial lights including mercury vapour, both high and low pressure sodium vapor lamps and unwanted natural light caused by the emission of neutral oxygen into our atmosphere (eg Skyglow) .

The OIII emits from 495.9 nm and 500.7 nm, so it is a blue-green color filter, therefore many images of planetary nebulae and supernova remnants are only taken with H-ALPHA and OIII filters; showing superb structural details while maintaining natural colors, the image thus taken looks like an RGB image.

Main use and performance

Suitable for observing most emission nebulae, planetary nebulae and supernova remnants.

Narrowband imaging can be obtained by combining the filters of the SHO set (H-ALPHA, OIII, SII), in lunar and light pollution conditions, in this way the equipment does not remain stationary for weeks .

The OIII filter does not eliminate the effects of light pollution and does not increase the brightness of the photographed object, but rather increases the contrast between the nebula and the night sky, making image processing easier.

This 6.5nm narrowband OIII filter is designed to be used in filter wheels, in filter holder drawers or directly on the camera (not valid for those not mounted in the cell)
Technical characteristics

Technical data

• Schott substrate material
• Thickness 2.0mm
• Surface quality: 60/40
• Fine optical polishing to ensure accurate 1/4 wavefront and <30 seconds parallelism on both surfaces
• OIII filter has 80% transmission, OIII line is 500 nm
• Precision out-of-band blocking