SVBONY SV227 1.25″ SHO 5nm Narrowband Filter Set (H-alpha, OIII, SII)

Product Overview

The SVBONY SV227 1.25″ SHO set is three 5 nm narrowband imaging filters, H-alpha at 656.3 nm, OIII at 500.7 nm and SII at 671.6 nm, for building Hubble-palette and bicolour images of emission nebulae. Each filter has a peak transmission of at least 90%, average blocking of OD5 across 300–1000 nm and a 26 mm clear aperture, in a thin 6061T aluminium cell with an M28.5 x 0.6 thread. The set weighs 140 g, and each filter 15 g.

Who It's For

This is a good match if you image emission nebulae with a monochrome camera and a 1.25″ filter wheel or drawer, especially from light-polluted skies where narrowband isolates the target lines from sky glow.

Key Features & Design

• Complete SHO set: H-alpha, OIII and SII in matching 5 nm bandwidths.
• ≥90% peak transmission: at each emission line.
• OD5 average cut-off depth: strong rejection of unwanted light from 300 to 1000 nm.
• Double-sided polishing and coating: single-piece substrates, not two-piece cemented, with 1/4λ surface flatness and 30″ parallelism.
• 26 mm clear aperture: in a thin metal cell to maximise the opening.

Optical Design

Each filter is an interference filter on a 1.85 mm substrate. Narrowing the passband to 5 nm around the target line raises the contrast of faint nebulosity against the background, and the OD5 blocking keeps light pollution and moonlight out of the frame. Surface quality is 60/40, with 1/4λ surface parallelism.

Recommended Uses

• SHO (Hubble palette) imaging of emission nebulae and supernova remnants.
• HOO bicolour imaging with the H-alpha and OIII filters.
• Imaging under city skies and around the Moon.

Compatibility and Accessory Notes

• Thread: M28.5 x 0.6 male, single thread, standard 1.25″ size (Φ31.75 x 7 mm cell).
• Filter holders: any 1.25″ filter wheel, drawer slider or camera nosepiece with the standard thread.
• Sensor size: 1.25″ filters suit small and medium sensors; larger sensors are usually paired with 2″ filters.

What's in the Box

• 1.25″ H-alpha filter x1
• 1.25″ SII filter x1
• 1.25″ OIII filter x1
• PP storage cases x3

Good to Know Before You Order

• Imaging filters: designed for camera imaging, with mono cameras getting the most from each line.
• Not for solar use.
• Wheel or drawer: a filter wheel or drawer makes changing between the three filters straightforward.

Frequently Asked Questions

Is it difficult to set up?

No. Each filter threads into a standard 1.25″ filter wheel position, drawer slider or camera nosepiece.

Can I use them with a colour camera?

They work, but a colour sensor records each line on only part of its pixels; a mono camera uses the full sensor for each filter.

What bandwidth are they?

5 nm for all three filters.

Bottom Line

In short: a matched set of 1.25″ 5 nm H-alpha, OIII and SII filters with ≥90% peak transmission and OD5 blocking, for narrowband nebula imaging.