The UHC (Ultra-High Contrast) broadband filter is designed to improve the visibility of various deep-sky objects. By selectively reducing the transmission of wavelengths of light pollutants, specifically those produced by artificial lightingsuch as mercury vapor lamps, both high & low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (sky glow).

The filter ishighly transparent in the main nebula emission lines at OIII (496nm and 500nm), H-beta (486nm), NII (654nm and 658nm), H-alpha(656nm) as well as SII (672nm). The filter is suitable for enhancing the contrast and details for both visual and photographic purpose insuburban and rural areas with heavy light pollution.

Main Use and Performance

• Suitable for color CCD cameras and unmodified DSLRs that accept 1.25″ filters.
• With narrower band-pass transmission gaps, this filter provides higher contrast than CLS filters.
• The UHC filter has a substantial red band-pass and offers superb views of objects like the Orion Nebula (M42)
• Light pollution filters do not eliminate the effects of light pollution or increase the object’s brightness. In many cases, they increase the contrast between nebula and night sky, not brightening the nebula.

Canon EOS FF Available for: EOS 5D/5DmarkII/III and 6D only

Nikon FFAvailable for:D600/D610/D700/D750/D800/D800E/D810/D810A/DF

Sony FFAvailable for:A7M/A7M2/A7M3/A7R/A7R2/A7R3/A7S/A7S2/A9

Specifications

• Schott substrate material
• Thickness 2.0 mm (1.25″/2″/36mm)
• Thickness 1.0 mm (Clip series)
• Surface Quality: 60/40 (Refer to MIL-O-13830)
• Fine-optically polished to ensure accurate 1/4 wavefront and <30 seconds parallelism over the both surfaces
• 95% transmission of main nebula emission lines (i.e. H-alpha 656nm, OIII 496nm and 500nm, SII 672nm and H-beta 486nm
• 0.1% transmission of off-band, specifically the major emission lines of artificial light pollution (i.e. Na 589nm, Hg 435nm and 578nm). Transmission of 0.1% is equivalent to OD3(Optical Density), and a high optical density value indicates very low transmission, and low optical density indicates high transmission.

Coating Parameter

• Multi-layers anti-reflection coating
• Non-cementing optical substrate coating
• Electron-beam gun evaporation with Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL (central wavele