SVBONY SV220 1.25″ 7nm H-Alpha & OIII Dual-Band Filter

Product Overview

The SVBONY SV220 1.25″ is a dual-band nebula filter that passes two 7 nm-wide bands centred on OIII (500.7 nm) and H-alpha (656.3 nm) and blocks the rest of the 300–1100 nm range to better than OD5. Peak transmission is above 90% at 500.7 nm and above 94% at 656.3 nm. The 1.85 mm substrate sits in a 1.25″ cell with a 26 mm clear aperture and a single M28.5 x 0.6 male thread, and the filter weighs 7 g.

Who It's For

This is a good match if you image emission nebulae with a one-shot colour camera and want narrowband-style contrast without moving to a monochrome camera and filter wheel, particularly from a light-polluted backyard or under a bright Moon.

Key Features & Design

• Two 7 nm passbands: OIII at 500.7 nm and H-alpha at 656.3 nm, the two strongest emission lines in most nebulae.
• OD5 out-of-band blocking: suppresses sodium and mercury street-light lines and sky glow.
• High transmission: above 90% (OIII) and above 94% (H-alpha) at peak.
• Optical quality: 60/40 surface quality and 1/4λ surface parallelism.
• Standard 1.25″ cell: M28.5 x 0.6 thread for 1.25″ nosepieces, filter wheels and drawers.

Optical Design

A dual-band filter is an interference coating with two narrow transmission windows. By passing only the OIII and H-alpha lines, it lets the nebula's own emission through while rejecting the broadband glow of artificial light and moonlight, which darkens the background and raises contrast. It does not add brightness to the target; it removes what competes with it. On a colour sensor the H-alpha signal lands in the red pixels and OIII in the green and blue pixels, giving a bicolour result in a single exposure. SVBONY notes that the OIII passband is relatively wide for its class, which favours signal collection in that channel.

Recommended Uses

• Emission nebulae: H II regions such as the North America, Rosette and Heart nebulae.
• Planetary nebulae and supernova remnants: strong OIII targets such as the Veil.
• Urban and moonlit imaging: extends usable nights for colour-camera imagers.

Compatibility and Accessory Notes

• Cameras: designed for one-shot colour (OSC) astronomy cameras; it also works with mono cameras as a combined Ha+OIII filter.
• Mounting: threads into any 1.25″ nosepiece, filter wheel or filter drawer with an M28.5 x 0.6 thread.
• Sensor size: the 26 mm clear aperture suits 1.25″-class sensors; larger sensors are better served by the 2″ SV220.
• Companion filter: SVBONY pairs it with the SV220 7nm SII & OIII filter for Hubble-palette (SHO) colour from an OSC camera.

If you are not sure whether a 1.25″ or 2″ filter suits your sensor and telescope, send us your camera model and we will work it out with you.

Good to Know Before You Order

• Imaging filter: it has no application in visual observing and is not a solar filter.
• Emission targets: galaxies, reflection nebulae and star clusters are broadband targets and gain little from it.
• Weight figure: SVBONY's spec table lists 7 g; a feature note on the same page lists 5.4 g.

Frequently Asked Questions

Is it difficult to set up?

No. It threads onto a 1.25″ camera nosepiece or into a filter wheel or drawer like any 1.25″ filter.

Does it work with a colour camera?

Yes. It is designed for one-shot colour cameras.

Will it help in the city?

Yes. The OD5 blocking suppresses street-light emission and sky glow, which is where dual-band filters do their most useful work.

Can I use it for visual observing?

It is an imaging filter and is not intended for visual use.

Bottom Line

In short: a 1.25″ 7 nm H-alpha and OIII dual-band filter with OD5 blocking that gives colour-camera imagers high-contrast emission-nebula data from light-polluted skies.