This Baader UHC-S / L-Booster Filter has been produced to aid in deep sky viewing. Extraneous light is reduced and contrast is upped; increasing the visibility of nebulae and stars.
The Baader UHC-S manages to improve on the contrast of the typical broadband Deep Sky filters. Sky background is darker, and contrast of emission nebulae are noticeably improved. The high transmission, sharp cut-offs, and more moderate 60nm passband of the Baader UHC-S filter retains a more natural view, yet significantly boosts overall contrast.
A common misperception is that deep sky viewing is limited to low power magnification and that image resolution is not as important as in planetary observation. In reality, high magnifications are very common and useful in studying fine details, particularly for the brighter diffuse and planetary nebulae. Baader UHC-S filters can take high magnifications, and stars retain their pinpoint sharpness.
Freedom from Ghosts and Halos: Baader Planetarium filters have always been halo and ghost free. Baader balances each dielectric coating stack to avoid the ghosts and annoying halos that plague other mfgr's filters.
Stackability: Unlike many other filters, Baader Planetarium filters are truly designed to be stacked and combined. This is possible due to the high optical quality and highly efficient anti-reflection multi-coatings. The ability to combine filters opens up many interesting possibilities, permitting unique spectral characteristics unachievable with any single filter.
Special Filter Cell: Baader's special filter cell design offers unique features that enhance their reliability and usability. Though difficult to produce, the ultra-thin filter cell results in the maximum possible clear aperture, in order to minimise vignetting (1¼" Filter clear aperture is 27mm, 2" Filter aperture is 45mm). The special threading has been designed to fit the wide variety of eyepieces and accessories (there is significant variation between the 1¼” filter threading used by eyepiece and accessory manufacturers). The front 'crown' of the filter incorporates milled notches which make handling and threading the filter a more secure operation in the dark.