Antlia SII 3 nm Pro 50 mm unmounted narrowband filter

The Antlia SII 3 nm Pro 50 mm is a professional astrophotographic filter designed specifically for capturing emission nebulae. It efficiently transmits light at a wavelength of 671.6 nm emitted by double ionized sulfur atoms, making it a crucial tool for astrophotography.

Crafted with meticulous attention to detail, the Antlia SII filter undergoes rigorous surface quality tests that adhere to stringent military standards. The exceptional care taken in its manufacturing is evident, ensuring top-notch performance and reliability. With an incredibly narrow half-band width of only 3 nm, this filter effectively eliminates unwanted components from sodium and mercury lamps while maintaining high transmission for the SII spectral line, which is of utmost importance in astrophotography.

Important note: The SII filter is not suitable for visual observation and should never be used as a solar filter under any circumstances.

Key Features of the Antlia SII 3 nm Pro 50 mm Filter:

Bandpass Filter: Made on a high-quality Schott substrate, this filter maximizes transmission for radiation at a wavelength of 671.6 nm.

Compatibility: Suitable for use with astrographs that have a high light intensity, reaching f/3 (e.g., RASA or Hyperstar).

Ultra-Narrow Bandwidth: The transmitted band has an exceptionally narrow half-width of 3 nm (FWHM), ensuring maximum contrast in captured images.

Efficient Light Pollution Reduction: With an equivalent optical density (OD5), this filter effectively cuts out light pollution at an impressive level of 99.999%.

Precise Technical Specifications: The Antlia SII filter possesses the following technical specifications:

• Filter Type: Bandpass filter
• Filter Diameter: 50 mm
• Filter Thickness: 3 ± 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 (as per MIL-O-13830 standard): 60/40
• Parallelism: 30 arc-seconds
• Execution Accuracy (RMS): λ/4

Included in the Set:

• Antlia SII 3 nm Pro 50 mm filter

Warranty:

The filter is backed by a 3-year manufacturer's warranty, covering delamination of the filter and substrate.