More about the series UHC-L...
Nebulae filters with maximum transmission, realistic star colours! Can also be used as a luminance filter for LRGB images
The Baader UHC-L filter is an Allround anti-light pollution filter that specifically blocks the main LED emissions in the blue part of the spectrum. The two transmission bands allow 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) to pass through, while blocking stray light from LED lamps and bluish car headlights as well as stray light from classic street lamps. Even the natural night sky glow (airglow/skyglow) of the atmosphere is largely blocked.
The UHC-L filter is primarily used for visual and photographic observation of emission nebulae (star-forming regions, planetary nebulae, supernova remnants). It is also interesting for comet observation: it allows both the OIII line at 501 nm and the two C2 lines at 511 nm and 514 nm, which are characteristic of the gas tail of many comets, to pass through.
This UHC-L is the successor to the proven, planoptically polished UHC-S filter. It therefore complements it with the advantages of CMOS optimisation and an improved transmission spectrum that is adapted to modern light pollution. It delivers a brighter image than many classic LPR (Light Pollution Rejection) filters and is therefore not only suitable for large, fast instruments, but also for light-polluted telescopes that cannot achieve a large exit pupil – this applies to both long-focus terrestrial viewing scopes and small telescopes that only have a barrel for 1.25" eyepieces.
Unlike narrower dual-band or tri-band filters, the image is also bright enough for high magnifications, with fewer stars being blocked out. For deep sky observers, this UHC-L filter is therefore the perfect visual complement to narrow-band OIII filters.
The UHC-L filter is also ideal for photographic use. It not only blocks terrestrial sources of light pollution, but also acts as a luminance filter (L filter), as it blocks all UV and IR transmission like a UV/IR blocking filter. An additional UV/IR blocking filter is therefore not necessary: cameras without a built-in UV/IR blocking filter deliver significantly sharper images with refracting telescopes. Both classic photographers and users of EAA/LiveStacking benefit from the increased sharpness of the stars and the better contrast of the nebulae, as well as the transmission for H-alpha.
The filter offers all the advantages of CMOS-optimised Baader filters:
- Increased contrast, tailored to typical CMOS quantum efficiency and s/n ratio
- Reflex-Blocker™ coatings for maximum insensitivity to retro-reflection from nearby auxiliary optics, even under the most adverse conditions
- Identical filter thickness to existing standards, with the utmost care taken to ensure homofocality
- Blackened edges all around, with filter front indicator in the form of a black outer edge on the telescope side to additionally prevent any reflection from light falling on the filter edge
- Each filter is individually precision-polished and coated, with a sealed coating edge (NOT cut from a larger plate, which would leave the coating edges exposed).
- Life-Coat™: even harder coatings to enable an age-resistant coating with an unlimited service life – even in the most adverse environments
