Baader Planetarium UHC-S / L-Booster Filter 31.7mm
Premium deep sky nebula filter from Baader Planetarium. Optically polished.
The Baader UHC-S manages to improve on the contrast of the typical broadband or so-called "Deep Sky" filters. Sky background is darker, and contrast of emission nebulae are noticeably improved, the high transmission, sharp cutoffs, 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 powers, and 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.