Optolong OIII CCD 3nm 2" Mounted Filter

The Optolong OIII 3nm CCD Filter (2") is a precision-engineered extra narrowband filter that isolates the Oxygen-III emission line at 500nm, allowing astrophotographers to reveal fine structural details in nebulae and supernova remnants with exceptional clarity and contrast. With a razor-thin 3nm bandwidth, this filter efficiently blocks light pollution and skyglow from both natural and artificial sources.

Designed for advanced CCD and CMOS monochrome imaging setups, the OIII 3nm filter excels in capturing the blue-green glow of ionized oxygen, which is prominent in star-forming regions. Its ultra-narrow profile drastically reduces the number of visible stars—emphasizing target nebulosity and fine filaments in even the most challenging skies.

Crafted using Optolong’s ion-assisted deposition and planetary rotation system, this filter ensures uniform coatings with high passband transmission and excellent optical density in the off-band regions. The durable 2" filter cell is constructed from CNC-machined, anodized metal with a 45mm clear aperture for edge-to-edge image fidelity.

• Filter Type: Extra Narrowband – OIII
• Center Wavelength: 500nm
• Bandwidth (FWHM): 3nm
• Transmission: High at 495.9nm & 500.7nm OIII lines
• Infrared Block: 700–1100nm
• 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 Quality: 60/40 (MIL-O-13830)
• Wavefront Accuracy: λ/4
• Parallelism: <30 arcseconds
• Coating Method: Electron-Beam Evaporation with Ion-Assisted Deposition
• Filter Cell: CNC-Machined, Sandblasted, Black Anodized Aluminum
• Certifications: RoHS, TUV Rheinland, Bureau Veritas

• Optolong OIII CCD 3nm 2" Filter
• Plastic Filter Case with EVA Foam Protection