This SII-CCD Filter is suitable for imaging of SII-regions from observation sites with light pollution and from dark sites as well. The contrast between an object glowing at 672nm and the background is increased significantly. 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 extremly 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 starcrowded regions of the milkyway.
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
Guaranteed Transmission of more than 90% at the SII Line (672 nm) Typical Transmission of 96% at the SII Line (672 nm)
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, non 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-Emissionline filters is the best way to take great images, as all kinds of light pollution can be blocked very effectively. Normally an H-alpha filter should be your first step into this amazing field of astrophotography! With a Narrowband H-alpha filter you will be able to take deep and high contrast images even with very heavy light pollution or with the full moon high 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 the narrowband set. 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 meaningfull application.
Operation of the filter
The filter blocks all unwanted light from artifical light-pollution, natural airglow and moonlight. Especially light from High and Low-Pressure Sodium and Mercury lights and all lines of natural airglow are 100% blocked. The filter increases the contrast between the sky-background.
