Optolong UHC 2.0″ light pollution Filter
1.Optolong UHC Introduction
The UHC (Ultra High Contrast) broadband filter is designed to improve the visibility of various deepsky objects. By selectively reducing the transmission of wavelengths of light pollutants, specifically those produced by artificial lightings including mercury vapor lamps, both high & low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow).
Main Use and Performance
Suitable for color CCD cameras and unmodified DSLRs.
UHC with narrower passband provides higher contrast than CLS. Thus it is more suitable for urban environment where you suffer from severe light pollution.
UHC has a substantial red passband and offer superb views for objects like the Orion Nebula (M42).
Light pollution filter 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.
WARNING: The filters of Optolong are not designed for sun observation. DO NOT LOOK AT THE SUN WITH OPTOLONG FILTER. You would be BLIND if you fail to observe the warning.
Sbustrate: optical glass
Blocking range: 300-700nm
Blocking depth: OD3, light pollution line blocking >99%
Surface quality: 60/40 (Refer to MIL-O-13830A, MIL-C-48497A)
Transmitted Wavefront RMS: ¼ λ
2. UHC Spectrum and Characteristic
How to read the chart?
▲The horizontal axis is the Wavelength in Nanometers(nm).
▲The vertical axis is transmission in %.
▲The RED line shows the line of H-alpha. Green line shows the emission of OIII. The artificial emission lines are shown in ORANGE.