Optolong UHC 2" Mounted Filter

The Optolong UHC (Ultra High Contrast) 2" Filter is designed to dramatically enhance the visibility of deep-sky objects by reducing the impact of both artificial and natural light pollution. This broadband filter blocks unwanted wavelengths from mercury and sodium vapor lamps as well as neutral oxygen emission (skyglow), allowing nebulae and galaxies to emerge in stunning clarity—even from light-polluted urban skies.

With a peak transmission of 95%, the filter selectively passes critical nebular emission lines such as OIII, H-Beta, H-Alpha, NII, and SII. The added strength of its red passband ensures spectacular performance on iconic targets like the Orion Nebula and North America Nebula, improving both contrast and color fidelity.

Engineered from precision-ground Schott B260 glass, the filter is treated with Optolong’s advanced ion-assisted deposition coatings for long-term wavelength stability, high durability, and scratch resistance. The ultra-thin CNC-machined cell offers a 45mm clear aperture, making it suitable for large-format imaging sensors and high-end optical systems.

• Filter Type: Broadband – UHC (Ultra High Contrast)
• Peak Transmission: 95%
• Passband: OIII, H-Beta, H-Alpha, NII, SII
• Off-band Rejection: <0.1% at Na (589nm), Hg (435nm, 578nm)
• 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
• Manufacturing System: Optolong Planetary Rotation Coating Process
• Certifications: RoHS Compliant, TUV Rheinland, Bureau Veritas

• Optolong 2" UHC Filter
• Protective Filter Case with EVA Foam Interior