• Superb light transmission of 96% at the SII 672nm spectral line, ensuring adequate capture of details.
• Half Width Half Maximum bandpass of 12nm to filter out wavelengths outside of the SII spectral range, making details even in light polluted locations more apparent.
• Blocks unwanted light from UV up to IR, thus removing excess stray light and scatter.
• Parfocal with other Astronomik filters making refocusing unnecessary when switching between different filters using the same imaging and optics configuration.
• Designed to work with optics up to f/3 focal ratio. Anything faster, the MaxFR version are recommended instead to account for band shifting.
• 1mm thickness.
• Moisture and scratch resistant.
• Includes small storage box to be protected from external damage when not in use.
• This configuration of the SII 12nm filter is 2" mounted.

The Astronomik 12nm SII Filter is geared for capturing images of cosmic regions that are rich in Sulfur II. Since it filters out wavelengths beyond the 672nm spectral line with a full width half maximum bandpass of 12nm,  it emphasizes the SII spectral line away from the rest of the spectral range so details become more apparent. Due to its extreme narrowband features, it is helpful for astrophotography even in light polluted areas since light pollution wavelengths are generally outside of this range. With a rocksolid 96% light transmission rate, imagers can be rest assured that no significant loss of light will miss hitting the camera sensor, thus ensuring exposures are crisp with maximum illumination consistent with the sensor quantum efficiency and full well capacity.