Optolong H-Alpha 3nm CCD 2" Filter

The Optolong H-Alpha 3nm CCD Filter (2") is an elite-grade narrowband filter engineered to isolate the critical H-alpha emission line at 656nm. With a bandwidth of just 3nm, it provides unparalleled contrast by eliminating almost all background noise from skyglow and artificial lighting—allowing astrophotographers to detect faint nebula structures with superb definition.

This filter is ideal for imaging emission nebulae and hydrogen-rich star-forming regions, delivering maximum signal-to-noise ratio when used with CCD or monochrome CMOS cameras. It’s particularly effective for creating high-fidelity SHO or Hubble Palette compositions when paired with OIII and SII filters.

Featuring Optolong’s signature multi-layer anti-reflection coatings applied via ion-assisted deposition, the H-Alpha 3nm filter ensures precise central wavelength performance, temperature stability, and exceptional durability. The ultra-thin 2" cell is CNC-machined and black anodized, offering a 45mm clear aperture for optimal field coverage and mechanical stability in demanding imaging setups.

• Filter Type: Extra Narrowband – H-Alpha
• Center Wavelength: 656nm
• Bandwidth (FWHM): 3nm
• Transmission: High at H-Alpha emission line
• 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 with Ion-Assisted Deposition
• Filter Cell: CNC-Machined, Sandblasted, Black Anodized Aluminum
• Certifications: RoHS, TUV Rheinland, Bureau Veritas
• Warning: Not for solar observation

• Optolong H-Alpha 3nm CCD 2" Filter
• Protective Plastic Case with EVA Foam Interior