CHF 399.00
Available by order — estimated delivery time: 1 week
The Antlia SII 3nm Pro filter optimizes the FWHM at 3nm. By reducing the bandwidth, this filter improves the contrast of emission targets by reducing spurious background signal. It is designed to deliver a transmission of 88% at the 672.4nm line, guaranteeing optimum signal and good nebula definition.
Wider narrowband filters often suffer significant transmission losses due to center wavelength shift (CWL). The 3nm Pro filter guarantees >88% transmission within ±1nm of the center band, enabling compatibility with lenses as fast as f/3 without significant signal loss.
Out-of-band rejection is rated OD5 (0.001%), ensuring an excellent signal-to-noise ratio and effective cutting of unwanted wavelengths. This filter is designed to limit halos around bright stars.
| Parameter | Value |
|---|---|
| Substrate | Optics, unglued monoblock |
| Thickness | 2mm ±0.05mm (1.25″, 2″, 31mm, 36mm), 3mm ±0.05mm (50mm, 50x50mm) |
| FWHM | 3nm |
| Center wavelength (CWL) | 672.4nm |
| Maximum transmission | >88% |
| Out-of-band discharge | OD5 (0.001%) from 300 to 1000nm |
| Surface quality | S/D 60/40 (MIL-O-13830 standard) |
| Transmitted wavefront | λ/4 or better |
| Parallelism | < 30 arcsec |
| Warranty | 3 years against delamination |
NEVER LOOK AT THE SUN WITH THIS FILTER. Serious eye damage may occur.
