Baader UHC-L Ultra-L Booster Filter
 Baader UHC-L Ultra-L Booster FilterBaader UHC-L Ultra-L Booster Filter 

Baader UHC-L Ultra-L Booster Filter

£84.00✓ 2 year warranty


Out of stock due 10-15 working days

"In the animal kingdom evolution can proceed at a rapid rate, but in technological development it can be executed at a comparativelv breakneck speed. Noticing that astronomers have been able to counter skyglow created by the mustard cast of sodium street lighting, civic designers have evolved the use of LED illumination with which to drown the wonders of the night sky.

But we will not be thwarted. The Baader UHCL/ Ultra-L booster filter is a new device from Baader that is fine-tuned to deal with a whole swathe of urban light pollution, including that from the new plague of LED radiation, in order to image the faint traces of comets and emission nebulae.

Despite battling unwanted light, the filter passes the standard O Ill nebula line at 501 nm, but also has windows for the two cometary C2 lines at 511nm and 514nm - and does this job without significant impact on star colours.

The filter comes in a range of sizes to suit the user's needs." 

Steve Ringwood writing for Astronomy Now magazine

About this product

Model:  baader_2961560
Part Number:  2961560

Baader UHC-L Ultra-L Booster Filter

This new filter rejects light pollution and blocks the main emissions from LED in the blue part of the spectrum.

The passband curve corresponds to a wide dual-band filter without distorting star colours. 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 blocking most 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 the latest technology (CMOS-optimised) and therefore blocks false light much more effectively than all previous UHC filters.

Use of the UHC-L filter: 

The application of the UHC-L has been designed mainly in the 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 and the two C2 lines at 511nm and 514nm, characteristic of many comets' gas tails.

This UHC-L filter is the successor to the well-proven plane-optical polished Baader UHC-S filter. It consequently complements it with the advantages of CMOS optimisation (no disturbing halos, blackened filter edges, Life-Coat™-coating) while providing an improved transmission spectrum adapted to modern LED light pollution. It gives a brighter image than many classic LPR (Light Pollution Rejection) filters. It is, therefore, suitable for large, fast instruments and smaller telescopes collecting less light, where a large exit pupil cannot be achieved. This applies to long-focal length telescopes and small aperture telescopes that only have an eyepiece socket for 1.25″ eyepieces. Unlike the single-line or dual-line narrowband filters, the image is also bright enough for high magnification while not diminishing the number of stars. Therefore, this UHC-L filter is the perfect visual complement to narrowband OIIIp-sky observers filters for dee.

The UHC-L filter is also excellent for photographic use. It does not just block polluting terrestrial light sources; it also serves as a luminance filter (L-filter) since it blocks all UV and IR transmission like a UV/IR cut filter. An additional UV/IR-cut filter is therefore unnecessary: Cameras without a built-in UV/IR-cut filter thus deliver significantly sharper images, particularly refracting telescopes. Both classical photographers and users of EAA/LiveStacking also benefit from the increased sharpness of stars, better contrast of nebulae, and improved transmittance in H-alpha.

Like all Baader CMOS-optimised filters, Baader UHC-L filters are plano-optically polished, with ultra-hard, sputtered dielectric coatings. Even a one-hour bath in boiling water cannot harm these filters! They are scratch-resistant and can be cleaned as often as desired.


  • Increased contrast, matched for typical CMOS quantum efficiency and s/n ratio
  • Reflex-Blocker™ coatings, for the largest ever freedom from halos, even under most adverse conditions concerning aux-optics
  • Identical filter thickness to existing standards, with utmost care for parfocality
  • Blackened edges all around, with filter-lead-side-indicator in the form of a black frontside outer rim, to additionally eliminate any reflection due to light falling onto the edge of a filter
  • Each filter is coated individually, with a sealed coating edge (NOT cut out of a larger plate with coatings left exposed, read more)
  • Life-Coat hard coatings provide a non-ageing coating for life – even in a most adverse environment
  • Ideal for deep-sky observers. This UHC-L filter is the perfect visual complement to narrowband OIII filters.

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