Pellucid Glimmer H-beta narrowband filter 36 mm, observatory grade

Specifications

Description

The Glimmer H-beta narrowband filter is a 36 mm unmounted glass element that passes a band about 8 nm wide centered on the hydrogen-beta emission line at 486.1 nm. Hydrogen-beta is one of the brighter visible lines in emission nebulae, so the filter admits much of the nebula's light while blocking most of the broadband skyglow and starlight that reach the sensor. The element is sized for holders and filter wheels that accept 36 mm round glass.

Emission nebulae shine at discrete wavelengths, while the sky background, scattered artificial light, and most stars emit across a continuous spectrum. A narrow passband therefore reduces the background signal by a large factor relative to the nebula. Exposure times that would be needed with a broadband camera can drop substantially under light-polluted skies, although the nebula itself does not become brighter. You will also notice that the filter removes much of the continuum, so stars appear dimmer and fewer than in unfiltered images.

The filter suits hydrogen-rich emission regions such as the Rosette, Heart, and Soul nebulae in long exposures, and it pairs with an OIII filter for bicolor work. It does not help with galaxies, star clusters, or reflection nebulae, which emit across broad bands. Handle the glass by its edges, keep the coated surface clean, and store it in its case when not in use. Check focus after each change because the filter alters the optical path. Peak transmission near 88 percent reflects coating quality, and the 2.0 mm glass thickness keeps the element flat under mounting pressure.

About this configuration

All configurations of the Pellucid Glimmer H-beta narrowband filter 36 mm share the same filter glass design; the options change the grade, the coating, and the case. 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 Glimmer 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.

A padded pouch is easy to open with cold fingers, which helps when you swap filters during a session. This is the 2024 edition, which revised the cell knurling and the case insert of the Glimmer line. A filter does not make objects brighter; it darkens the sky background more than the target, which raises contrast.

What's in the box

• H-beta filter, 36 mm unmounted glass element
• Protective storage case
• Lens tissue
• Test report with measured transmission curve
• Padded pouch

Compatibility notes

• Fits holders and filter wheels that accept 36 mm unmounted round elements.
• Requires a focus check after insertion because the filter changes the optical path.
• Intended for imaging of emission nebulae in telescopes of 100 mm aperture and larger.