Baader UHC-L / Ultra L Booster Filter 2

Baader UHC-L / Ultra L Booster Filter 2"

Visual and photographic 2" UHC-L nebula filter with highest transmision.
Ultra high contrast L-filter, blocks city lights and increases contrast of nebulae and comets (C2 lines)
Can be used as LED-optimized luminance filter for LRGB imaging with skyglow suppression
Produces a much brighter image than classical nebula filters
Passage in the blue for better suppression of LED illumination
Also ideal for deep sky observers. This UHC-L filter is the perfect visual complement to narrowband OIII filters
Reflex-Blocker™ hard-coated and plano-optically polished - with sealed coating edges (Life-Coat™).
Blackened edges all around, with filter front indicator in the form of a telescope-side black outer edge
 
Baader UHC-L DeepSky Filter
Plano-optically polished

All Baader UHC-L DeepSky Filters.
1¼", 31mm, 36mm, 2", 50.4 mm, 50x50 mm, 65x65mm
Baader UHC-L nebula filter with highest transmission, realistic star colors, also usable as LED optimized luminance filter for LRGB imaging.
The Baader UHC-L filter is the classic "all-round anti-light pollution 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, but without distortion of the star colors. The two passbands let pass 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 vaporized with the latest technology (CMOS-optimized) and therefore blocks stray light much more effectively than all previous UHC filters.

Use of the UHC-L filter
The application of the UHC-L filter is mainly in visual and photographic observation of emission nebulae (star forming regions, planetary nebulae, supernova remnants). Its use in comet observation is also interesting: it passes both the OIII line at 501nm and the two C2 lines at 511nm and 514nm, which are characteristic of the gas tails of many comets.

This UHC-L is the successor of the well-proven plano-optical polished UHC-S filter. It consequently complements it with the advantages of CMOS optimization (no disturbing halos, blackened filter edges, Life-Coat™ coating) while providing an improved transmission spectrum adapted to modern light pollution. It provides a brighter image than many classic LPR (Light Pollution Rejection) filters and is therefore not only suitable for large, fast instruments, but also for low-light telescopes on which a large exit pupil cannot be achieved - this applies to both long-focal length telescopes and small telescopes that only have an eyepiece socket for 1.25" eyepieces. Unlike narrower-band dual-band or tri-band filters, the image is also bright enough for high magnifications, and stars are less faded out. For deep-sky observers, therefore, this UHC-L filter is the perfect visual complement to narrowband OIII filters.

The UHC-L filter is also excellent for photographic use. It serves not only to block terrestrial interference light sources, but at the same time 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 not necessary: Cameras without a built-in UV/IR-cut filter thus deliver significantly sharper images on refracting telescopes. Both classical photographers and users of EAA/LiveStacking benefit from the increased image sharpness of stars and better contrast of nebulae, as well as the transmittance for H-alpha.

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

The Baader UHC-L / Ultra-L-Booster filter offers all the advantages of the CMOS-optimized Baader filters:
Increased contrast, matched to typical CMOS quantum efficiency and s/n ratio.
Reflex-Blocker™ coatings, for greatest possible insensitivity to retro-reflection from nearest auxiliary optics, even under the most adverse conditions
identical filter thickness to existing standards, with utmost care for homofocality
blackened edges all around, with filter-front indicator in the form of a telescope-side black outer edge, to additionally avoid any reflection by light falling on the filter edge
each filter individually fine-optically polished and coated, with sealed coating edge (NOT cut out of a larger plate - with thus exposed coating edges - see more here)
Life-Coat™: even harder coatings to provide an aging resistant coating over an unlimited lifetime - even in the most hostile environments.
 
MANUFACTURER Baader Planetarium
ITEM NUMBER (#) 2961563
EAN CODE 4047825048240
NET WEIGHT (KG) 0.012
TRANSMISSION RANGE multi-band (see spectrum figure)
FILTER THICKNESS (WITHOUT SOCKET) 2 mm
COATING (DEHUMIDIFICATION) Reflex-Blocker™ hard coated, dielectric coated, plano-optical polished.
FILTER SIZE 2 in.
APPLICATION TYPE CMOS, contrast enhancement, light pollution (LPR), luminance.
FILTER SIZE mounted (LPFC 6mm)
FILTERTYPE Bandpass
SINGLE OR SET? single filter
FILTER SHAPE round