SVBONY SV227 2″ SII 5nm Narrowband Filter

Product Overview

The SVBONY SV227 SII is a 2″ narrowband imaging filter with a 5 nm passband centred on the 672 nm sulfur II emission line. Peak transmission is at least 90%, blocking is ≥OD5 across 300–1000 nm, and the clear aperture is 44 mm. The 1.85 mm substrate sits in a CNC-machined, black-anodised cell with an M48 x 0.75 thread, and SVBONY lists the net weight as 12.5 g.

Who It's For

This is a good match if you image emission nebulae with a monochrome camera and are building SHO (Hubble palette) data, using a 2″ filter wheel or drawer to cover a larger sensor.

Key Features & Design

• 5 nm at 672 nm: isolates sulfur II emission from light pollution and moonlight.
• ≥90% peak transmission and ≥OD5 blocking from 300 to 1000 nm.
• Coatings: multi-layer anti-reflection coatings applied by electron-beam evaporation with ion-assisted deposition.
• Optical glass: SVBONY specifies German optical glass, 60/40 surface quality, 1/4λ surface parallelism and 30″ parallelism.
• Metal cell: CNC-machined, black-anodised and laser-engraved.

Optical Design

SII is usually the faintest of the three SHO lines, so a narrow 5 nm passband and deep blocking are what keep the background dark enough to record it. The interference coating passes the 672 nm line at ≥90% while rejecting the rest of the 300–1000 nm range at ≥OD5, which also blocks the near infrared that a separate IR-cut filter would otherwise handle.

Recommended Uses

• SHO imaging of emission nebulae and supernova remnants alongside H-alpha and OIII.
• Imaging from light-polluted skies or with the Moon up.

Compatibility and Accessory Notes

• Thread: M48 x 0.75, single thread, standard 2″ size.
• Holders: 2″ filter wheels, filter drawer sliders and 2″ nosepieces.
• Matching filters: SVBONY makes the SV227 2″ H-alpha and OIII 5 nm filters and a 2″ SHO set.

Good to Know Before You Order

• Focal ratio: SVBONY lists it as unsuitable for telescopes faster than f/4.
• Not for solar use.
• This listing is the filter only; SVBONY also offers it with a 2″ holder.

Frequently Asked Questions

Is it difficult to set up?

No. It threads into a 2″ filter wheel position, drawer slider or nosepiece like any standard M48 filter.

Can I use it on an f/3.6 astrograph?

SVBONY rates it for f/4 and slower.

Do I still need an IR-cut filter?

No. The ≥OD5 blocking covers the near infrared.

Bottom Line

In short: a 2″, 5 nm SII filter at 672 nm with ≥90% peak transmission and ≥OD5 blocking, for SHO imaging at f/4 and slower.