Optolong OIII CCD 6.5nm 2" Mounted Filter

The Optolong OIII 6.5nm CCD Filter (2") is designed to isolate the critical Oxygen III emission line at 500nm, making it indispensable for high-contrast imaging of planetary nebulae, supernova remnants, and star-forming regions. Its extra-narrow 6.5nm bandwidth allows faint OIII structures to emerge from even the most light-polluted skies.

Built for advanced CCD and monochrome imaging, this filter excels when paired with H-Alpha and SII filters to recreate false-color SHO compositions akin to the iconic Hubble palette. Its ultra-thin filter cell is CNC-machined from black anodized aero-metal, ensuring mechanical precision and durability without adding optical stress.

Thanks to Optolong’s planetary rotation coating system and ion-assisted deposition technology, the filter delivers high pass-band transmission while aggressively suppressing off-band light—including skyglow and emissions from mercury and sodium vapor lamps. Whether you're imaging from a city or a remote dark site, this 2" OIII filter will take your narrowband captures to the next level.

• Filter Type: Extra Narrowband – OIII
• Center Wavelength: 500nm
• Bandwidth (FWHM): 6.5nm
• Transmission at OIII Line: ≥80%
• Infrared Block: 700–1100nm (built-in)
• Off-band Rejection: <0.1% at Hg (435nm, 578nm), Na (589nm)
• Filter Size: 2" (50.8mm)
• Clear Aperture: 45mm
• Substrate: Schott B260 Optical Glass
• Glass Thickness: 2.0mm
• Surface Accuracy: λ/4
• Parallelism: <30 arcseconds
• Surface Quality: 60/40 per MIL-O-13830
• Coating Method: Electron-Beam with Ion-Assisted Deposition
• Filter Cell: CNC-Machined, Sandblasted, Black Anodized Aluminum
• Certifications: RoHS Compliant, TUV Rheinland, Bureau Veritas

• Optolong 2" OIII CCD 6.5nm Filter
• Plastic Filter Case with EVA Foam Interior