The SVBONY SV227 SII filter is a 2″ narrowband astrophotography filter with a 5 nm bandwidth, designed to isolate the sulphur-II emission line at 672.4 nm. It is intended for deep-sky imaging of emission nebulae, where strong suppression of light pollution and background sky glow is required.
5 nm Narrowband Precision
With a narrow 5 nm passband, the SV227 SII filter provides high contrast by isolating the sulphur-II emission wavelength while rejecting surrounding light. This makes it well suited for imaging faint nebular structures under both urban and dark-sky conditions.
High Transmission & Deep Blocking
The filter delivers peak transmission of ≥90% at the SII wavelength, combined with deep out-of-band blocking of OD5 or greater. This helps reduce background noise and improve signal-to-noise ratio during long exposure imaging sessions.
Precision Optical Construction
Manufactured from high-quality optical glass, the SV227 SII filter is designed to maintain optical flatness and parallelism across the imaging field. This helps minimise focus shift and star distortion when used in demanding astrophotography setups.
Standard 2″ Thread Compatibility
The filter features a standard M48 × 0.75 (2″) thread, making it compatible with most 2″ filter wheels, filter drawers, and imaging adapters used with astronomy cameras and telescopes.
Spectral Performance
The transmission profile is precisely centred at 672.4 nm, ensuring accurate isolation of the sulphur-II emission line commonly used in SHO and other narrowband imaging workflows.
Installation & Use
The filter installs directly into compatible 2″ threaded components and is suitable for use with monochrome astronomy cameras and narrowband imaging workflows.
Imaging Examples
Below are example comparisons demonstrating the effect of the SII filter on deep-sky imaging results.
Important Notes
- Not suitable for solar observation.
- Not recommended for optical systems faster than f/4.
