Antlia SII 3 nm Pro 1,25" narrowband filter

The Antlia SII 3 nm Pro 1.25" is a specialized astrophotography filter designed to transmit light at a precise wavelength of 671.6 nm, which is emitted by double ionized sulfur atoms. This wavelength is particularly important for capturing images of emission nebulae.

Crafted with the utmost precision, this filter, like other Antlia products, undergoes rigorous surface quality testing, meeting the strictest military standards. Notably, it boasts an exceptionally narrow half-band width of just 3 nm. This unique feature enables the filter to effectively eliminate unwanted components from sodium and mercury lamps while ensuring a high transmission rate for the SII spectral line—a critical aspect in astrophotography.

Please note that the SII filter is not suitable for visual observation and should never be used for solar observation.

Key Features of the Antlia SII 3 nm Pro 1.25" Filter:

• Bandpass filter crafted on a top-quality Schott substrate, maximizing transmission at 671.6 nm.
• Compatible with astrographs with light intensity up to f/3 (e.g., RASA or Hyperstar).
• Exceptionally narrow transmitted band half-width (FWHM = 3 nm) for maximum contrast.
• Equivalent optical density OD5, ensuring a 99.999% efficiency in cutting out light pollution.

Technical Specifications:

Filter Type: Bandpass Filter

Filter Diameter: 1.25"

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 (per MIL-O-13830 standard): 60/40

Parallelism: 30 arcseconds

Execution Accuracy (RMS): λ / 4

Kit Components:

Antlia SII Filter 3 nm Pro 1.25"

Warranty:

The manufacturer offers a 3-year warranty, covering delamination of the filter and substrate.