The Chroma S-II, H-alpha, O-III 8 nm 31 mm unmounted filter set is a high-grade narrowband filter set designed for astrophotography of emission objects. The set includes the three main lines used in SHO imaging: S-II, H-alpha and O-III. The filters allow selective imaging of emission nebulae, planetary nebulae and supernova remnants while reducing the influence of light outside the selected spectral ranges, including part of urban light pollution.

Key features

• set of three narrowband filters for SHO astrophotography
• includes S-II, H-alpha and O-III filters with a nominal 8 nm transmission band
• designed for imaging emission nebulae, planetary nebulae and supernova remnants
• enables deep-sky imaging in selected emission lines
• reduces the influence of light outside the transmission band, making imaging easier also under urban light pollution
• unmounted version with a 31 mm diameter
• intended for demanding astrophotographic applications, especially with monochrome cameras

Kit contents

• Chroma S-II 8 nm 31 mm unmounted filter
• Chroma H-alpha 8 nm 31 mm unmounted filter
• Chroma O-III 8 nm 31 mm unmounted filter

Technical specifications

• manufacturer: Chroma
• product name: SII Ha OIII - 8nm
• SKU / manufacturer part number: 27111
• set type: SHO narrowband filter set
• number of filters in the set: 3
• filters included: S-II, H-alpha, O-III
• nominal transmission band: 8 nm
• S-II line: approx. 672.4 nm
• H-alpha line: 656.3 nm
• O-III line: 500.7 nm
• maximum S-II transmission based on the manufacturer’s spectral data: approx. 98.7%
• maximum H-alpha transmission based on the manufacturer’s spectral data: approx. 96.5%
• maximum O-III transmission based on the manufacturer’s spectral data: approx. 94.5%
• filter diameter: 31 mm
• format: unmounted

The Chroma S-II, H-alpha, O-III 8 nm 31 mm set is intended for astrophotographers who want to image emission objects in the classic SHO palette with high spectral selectivity.