SVBONY SV227 2″ H-Alpha 5nm Narrowband Filter

Product Overview

The SVBONY SV227 H-alpha is a 2″ narrowband imaging filter with a 5 nm passband centred on the 656.3 nm hydrogen-alpha 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 thin CNC-machined, black-anodised aluminium 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, whether for H-alpha luminance, HOO bicolour or full SHO, and use a 2″ filter wheel or drawer to cover a larger sensor.

Key Features & Design

• 5 nm at 656.3 nm: isolates hydrogen-alpha emission from sodium and mercury-vapour light pollution.
• ≥90% peak transmission and ≥OD5 blocking from 300 to 1000 nm.
• Multi-layer anti-reflection coatings on German optical glass.
• Thin aluminium cell: maximises clear aperture; CNC-machined, black-anodised and laser-engraved.
• Surface quality 60/40, 1/4λ surface parallelism and 30″ parallelism.

Optical Design

H-alpha is the brightest line in most emission nebulae, and a 5 nm passband records it with a very dark background even under city skies. The interference coating passes 656.3 nm at ≥90% and rejects the rest of the 300–1000 nm range at ≥OD5, so no separate IR-cut filter is needed.

Recommended Uses

• H-alpha imaging of emission nebulae, on its own or as luminance for colour data.
• HOO and SHO imaging alongside OIII and SII filters.
• 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″ OIII and SII 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 is a night-sky imaging filter, not a solar H-alpha filter.
• 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 look at the Sun with it?

No. It is a deep-sky imaging filter; solar H-alpha viewing needs a dedicated solar telescope or filter system.

Will it work with a colour camera?

Yes, though a colour sensor records H-alpha on its red pixels only; a mono camera uses every pixel.

Bottom Line

In short: a 2″, 5 nm H-alpha filter at 656.3 nm with ≥90% peak transmission and ≥OD5 blocking, for nebula imaging at f/4 and slower.