SVBONY SV132 1.25″ H-Beta 25nm Nebula Filter

Product Overview

The SVBONY SV132 1.25″ (item W9102A) is an H-Beta narrowband filter for visual observing. It transmits 80% at 486 nm — the hydrogen-beta emission line — with a 25 ± 3 nm bandwidth, and holds mercury (435 nm, 578 nm) and sodium (589 nm) lines to 0.1% transmission. The 1.85 mm glass is double-side polished to 1/4-wave accuracy and coated in a planetary-rotation chamber for an even coating, mounted in a metal cell with the standard M28.5 × 0.6 1.25″ thread.

Who It's For

This is a good match if you observe faint emission nebulae visually through a moderate- to large-aperture telescope with 1.25″ eyepieces, and want the H-beta-bright objects — the Horsehead and California nebulae above all — to separate from the sky background.

Key Features & Design

• 486 nm H-beta passband: 25 ± 3 nm FWHM with 80% transmission at the line.
• Light-pollution rejection: 0.1% transmission at the Hg 435/578 nm and Na 589 nm lines.
• Double-side polished, 1/4 wave: with tight parallelism, which SVBONY credits with halo-free views around bright stars.
• Uniform vacuum-deposited coating: applied with a planetary rotation system.
• Metal cell, M28.5 × 0.6: fits 1.25″ eyepieces and threaded diagonal barrels.

Recommended Uses

• The Horsehead Nebula (B33) against IC 434.
• The California Nebula (NGC 1499).
• Other emission nebulae: SVBONY also lists M42, planetary nebulae and supernova remnants among suitable targets.

Compatibility and Accessory Notes

• Thread: M28.5 × 0.6, for 1.25″ eyepieces and threaded 1.25″ diagonal barrels.
• Telescope: SVBONY recommends moderate to large apertures and dark skies for the faintest targets.
• 2″ version: SVBONY also makes the SV132 in 2″.

Good to Know Before You Order

• Specialist filter: H-beta enhances a relatively short list of objects; an OIII or UHC-type filter covers more nebulae.
• Aperture and sky: the faint H-beta targets reward larger apertures and dark sites.
• Weight: not published by SVBONY.

Frequently Asked Questions

Is it difficult to set up?

No. Thread it onto the bottom of a 1.25″ eyepiece or into a threaded diagonal barrel.

What will an H-Beta filter show me?

Mainly nebulae that are bright in hydrogen-beta, with the Horsehead and California nebulae the best-known examples.

Does it block light pollution?

It holds the main mercury and sodium lines to 0.1%, though the faintest H-beta targets still look best from dark skies.

Will it fit my eyepieces?

It fits any 1.25″ eyepiece with the standard M28.5 × 0.6 filter thread.

Bottom Line

In short: a 1.25″, 25 nm H-Beta filter passing 80% at 486 nm and blocking Hg and Na lines to 0.1%, made for bringing out the Horsehead, California and other H-beta nebulae.