Pellucid Nocturne UHC nebula filter 1.25 in, observatory grade

Specifications

Description

The Nocturne UHC is an ultra-high contrast nebula filter in a 1.25 in threaded cell. Its passband is about 22 nm wide and sits in the blue-green part of the spectrum, covering the doubly ionized oxygen lines at 496 and 501 nm and the hydrogen-beta line at 486 nm. It also passes the hydrogen-alpha line at 656 nm in the deep red, and it blocks much of the broadband light from streetlights and sky glow.

Emission nebulae radiate strongly at these narrow wavelengths, while the sky background spreads its light across the spectrum. The filter suppresses the background and keeps most of the nebular light, so the contrast between the two increases. The nebula does not gain brightness, but the sky around it darkens, which lets faint outer structure stand out. Good targets include the Orion Nebula, the Lagoon and Trifid nebulae, the Cygnus Loop, and planetary nebulae such as the Ring and the Dumbbell.

The filter does not help with galaxies, star clusters, or reflection nebulae, which emit across a broad range of colors. On those objects it dims the view without adding detail. Stars also appear slightly greenish through the filter. The cell threads into any 1.25 in eyepiece barrel or the nosepiece of a 1.25 in diagonal, and the glass carries a multi-layer interference stack on one face and an anti-reflection layer on the other.

Under moderately dark skies and in a telescope of 100 mm aperture or larger, you will notice the effect most clearly. Many observers find a UHC filter a practical first nebula filter, since it works on a wide range of emission and planetary nebulae.

About this configuration

This listing covers one configuration of the Pellucid Nocturne UHC nebula filter 1.25 in, defined by its grade, coating, case, and edition year. The observatory grade comes with a measured transmission curve for the individual filter in the box. Observatory grade glass has the tightest flatness tolerance in the Nocturne line, which suits imaging with long focal lengths. The standard coating is applied to the filter side of the glass, with a single anti-reflection layer on the back.

The filter ships in a clear plastic case that keeps dust off the glass between sessions. This is the 2024 edition, which revised the cell knurling and the case insert of the Nocturne line. The transmission figures in the specifications apply to every configuration of the Nocturne line.

What's in the box

• UHC filter in 1.25 in threaded cell
• Padded storage case
• Test report with measured transmission curve
• Plastic storage case

Compatibility notes

• Threads into 1.25 in eyepieces, diagonals, and filter wheels (M28.5 x 0.6).
• Most effective in telescopes of 100 mm aperture and larger.