Antlia SII 3 nm Pro 31 mm unmounted narrowband filter

The Antlia SII 3 nm Pro 31 mm filter is a specialized tool for astrophotography, specifically designed to capture the 671.6 nm wavelength emitted by double ionized sulfur atoms in emission nebulae. This professional astrophotographic filter is crafted with utmost precision, undergoing rigorous surface quality tests that adhere to strict military standards.

One of the standout features of this filter is its remarkably narrow half-band width of just 3 nm. This attribute allows the filter to effectively eliminate unwanted components from sodium and mercury lamps, while maintaining a high transmission ¶Ci ± for the essential SII spectral line, crucial in astrophotography.

However, it is essential to note that the SII filter is not suitable for visual observation and should never be used for observing the sun.

The Antlia SII 3 nm Pro 31 mm filter boasts several key features:

It is a bandpass filter manufactured on a high-quality Schott substrate, ensuring maximum transmission for radiation at the 671.6 nm wavelength.

It is compatible with astrographs that have a high light intensity reaching f/3, such as RASA or Hyperstar.

The transmitted band has an incredibly narrow half-width of 3 nm, resulting in maximum contrast.

It possesses an equivalent optical density (OD5) that efficiently combats light pollution, cutting it out at a remarkable 99.999% level.

Technical Specifications:

• Filter Type: Bandpass filter
• Filter Diameter: 31 mm
• Filter Thickness: 2 ± 0.05 mm
• Filter Shape: Round
• Transmitted Bands: SII (671.6 nm)
• Peak Transmittance (CWL): 671.6 nm
• Half Bandwidth (FWHM): 3 nm
• Maximum Transmission: >88%
• Blocked Bands: Mercury lamps (435.8 nm, 546.1 nm, 577 nm, 578.1 nm), Sodium lamps (598 nm, 589.6 nm, 615.4 nm, 616.1 nm)
• Light Pollution Blocking Efficiency: >99.999%
• Equivalent Optical Density for Blocked Lines: OD5 (300 - 1000 nm)
• Surface Quality Index (according to MIL-O-13830 standard): 60/40
• Parallelism: 30"
• Execution Accuracy (RMS): λ/4

Included in the Set:

• Antlia SII 3 nm Pro 31 mm filter

Warranty:

The Antlia SII 3 nm Pro 31 mm filter comes with a manufacturer's warranty of three years, covering any delamination issues with the filter and substrate.