ZWO H-Alpha SII OIII filter set 31 mm loose filters

ZWO H-Alpha SII OIII filter set 31 mm loose filters contains three narrow-band interference filters (H-Alpha 656 nm, S II 672 nm and O III 501 nm) that block ambient light and capture faint nebulae in contrast. With a bandwidth of 7 nm, capture detailed structures in hydrogen nebulae, planetary nebulae and supernova remnants, even in urban light pollution.

Key benefits
✓ Narrowband filters for maximum contrast enhancement in H-Alpha, S II and O III
✓ 7 nm half-value bandwidth suppresses unwanted light without signal loss
✓ Homofocal design fits seamlessly with ZWO LRGB and color filters
✓ Loose 31 mm filters fit any standard filter wheel
✓ Aluminum housing for secure mounting and minimal reflection

Practical application
Combine with a monochrome ZWO ASI camera and filter wheel to automatically switch H-Alpha, S II and O III exposures. Ideal for deep neon shots with added detail and contrast, even under backlit night skies.

Technical specifications
- Format: 31 mm loose filters
- Filters: H-Alpha 656 nm, S II 672 nm, O III 501 nm
- Bandwidth: 7 nm (half value)
- Transmission: 80 %
- Housing: aluminum
- Application: narrowband astrophotography (photographic)