Antlia SII 3.5nm Filter 1.25"
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Vai al moduloAntlia SII 3.5nm Filter 1.25" – Ultra-Narrow Band for Astrophotography
The Antlia SII 3.5nm filter is an ultra-narrow band filter centered on the ionized sulfur emission line at 671.6nm, with a bandwidth of just 3.5nm. The extremely narrow bandwidth guarantees transmission above 88% on the SII line and out-of-band blocking of OD3 (0.1%) from 300 to 1100nm, for maximum contrast even under the most light-polluted skies.
Designed by Antlia specifically for new-generation CMOS cameras and fast telescopes down to f/2.0, the filter uses a monolithic, non-glued Schott optical substrate with double-sided polishing and multi-layer coating. The edge is hand-blackened to eliminate reflections at the edges – a distinctive feature of Antlia's build quality.
The SII component of the SHO set (H-Alpha + OIII + SII), it enables images in the Hubble Palette with exceptional detail in the sulfur structures of emission nebulae, supernova remnants and planetary nebulae.
Key Features
- 3.5nm bandpass – maximum contrast and light pollution suppression
- Transmission >88% on the SII line at 671.6nm
- OD3 (0.1%) blocking from 300 to 1100nm
- Monolithic, non-glued Schott substrate, parallel ±0.05mm
- Hand-blackened edges to eliminate stray light and halos
- 1.25" mount (M28.5x0.6), compatible down to f/2.0
Technical Specifications
| Filter type | Ultra-narrow band SII (Sulfur II) |
| Center wavelength | 671.6nm |
| Bandpass (FWHM) | 3.5nm |
| SII transmission | >88% |
| Out-of-band blocking | OD3 (0.1%) @ 300–1100nm |
| Format | 1.25" (mounted, M28.5x0.6) |
| Substrate | Schott, 2mm ±0.05mm thickness |
| Surface quality | 60/40 (MIL-O-13830) |
| Flatness | 1/4λ |
| Parallelism | 30" |
| Coating | Multi-layer nano-coating, double-sided |
| Focal ratio | Down to f/2.0 |
| Recommended use | Mono CCD/CMOS, SHO imaging, Hubble Palette |