Astronomik SII 6nm Narrowband Filter

Enhance your astrophotography with the Astronomik SII 6nm Narrowband Filter. Designed to isolate Sulfur II emissions, this high-quality filter allows you to capture stunning nebula details even in light-polluted areas. Its 6nm bandwidth ensures optimal signal-to-noise ratio, while the precision coating technology prevents halos and reflections. Elevate your celestial imaging and reveal the hidden beauty of the universe with the Astronomik SII 6nm Narrowband Filter.

Due to the combination of the narrow bandwidth of 6nm and the high transmission of typically 96% the filter gives you an enormous contrast boost, as all unwanted light from other wavelengths than 672nm is blocked form UV up to the IR. This results in an extremely dark background.
The FWHM of 6nm is matched to give you optimal performance with CCD and CMOS sensors with a very low dark current! The 6nm filter is the best choice if you are observing from a heavily light polluted site or if you are imaging faint objects in star-crowded regions of the Milky Way.

Due to the new MFR coating technique you may use one single filter on all instruments up to f/4 without a significant reduction in performance.

Technical data of the filter:

• Guaranteed Transmission of more than 90% at both SII lines (671,7nm und 673,0nm)
• Typical Transmission of 94% at both SII lines (671,7nm und 673,0nm)
• Full-Width-Half Maximum (FWHM): 6nm
• perfect blocking of unwanted light from UV up to the IR
• Parfocal with all Astronomik filters
• MFR Coating technique: Usable with all optics up to f/4
• Thickness of 1mm
• Not sensitive to moisture, scratch resistant, not aging
• Optically polished substrate, striae-free and free of residual stresses
• High quality storage box

Imaging with Narrowband-Emission line Filters
If you have to observe from light polluted sites (like most of us...), imaging with Narrowband-Emission line filters is the best way to take great images, as all kind of light pollution can be blocked very effective! Normally, an H-alpha filter should be your first step into this amazing field of astrophotography! With an Narrowband H-alpha filter you will be able to take deep and contrasty images even with very heavy light pollution or with the full moon high up in the sky!
If you look at other astrophotos, an H-alpha is the best choice for all nebulas glowing red! An OIII filters expands your imaging possibilities, as you are able to image all greenish/blueish structures. Planetary nebulas and star forming regions are great targets! The SII filters completes your HSO-set of filters. With these three filters you are able to process your images like the ones from the Hubble space telescope!
The h-beta filter is not available in a 6nm version, as this filter has nearly no meaningful application. To illustrate this, there are two images shown below: Both were taken with a unmodified Canon 650D. Even as the camera has a sensitivity of less than 10% at H-alpha, there is some signal und structure in the h-alpha image, while you cannot see anything on the image taken with an H-beta filter!