Baader UHC-L Nebula filter with highest transmission, realistic star colors, also usable as highly effective LED-optimized luminance filter for LRGB imaging.The Baader UHC-L filter is the classic all-round "light pollution rejection filter", but now also blocked against the main LED emissions in the blue part of the spectrum. The passband curve corresponds to a wide dual-band filter without distorting star colors. The two passbands transmit all light emitted by the known gas nebulae (the H-alpha and H-beta lines of fluorescent hydrogen as well as the OIII line of oxygen), while both the atmospheric most disturbing stray light from LED lamps and intense bluish car headlights as well as further stray light from classical street lamps and the natural night sky glow (airglow/skyglow) of the atmosphere are blocked to a large extent. At the same time, the UHC-L filter is coated with latest technology (CMOS-optimized) and therefore blocks false light much more effective than all previous UHC filters.Less ThanbRGreater ThanUse of the UHC-L filterLess ThanbRGreater ThanThe application of the UHC-L happens mainly in visual and photographic observation of emission nebulae (star forming regions, planetary nebulae, supernova remnants) under medium to highly polluted skies. Its use is also interesting for comet observation : It passes the OIII line at 501nm as well as the two C2 lines at 511nm and 514nm which are characteristic for the gas tail of many comets.Less ThanbR