Astronomik S-II 6nm Imaging Filter - Sony Alpha 7 Clip Filter
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The Astronomik SII filter is ideal for imaging nebulae showing sulfur emissions from both light-polluted and dark observation sites. It significantly enhances the contrast between objects emitting light at 671.7nm and 673nm (SII lines) and the sky background. The Astronomik SII filter completely filters out the emission lines from high- and low-pressure sodium (Na)- and mercury (Hg)-vapor lamps, as well as all lines of natural airglow and most of the distracting moonlight. For particularly high-contrast results, the Astronomik SII filter is optimised to prevent H-alpha light from passing through.
With a narrow bandwidth of either 12nm or 6nm and high transmission rates, the filter effectively blocks all unwanted light from wavelengths other than 671.7nm and 673nm from ultraviolet (UV) to infrared (IR).
Difference between Astronomik 12nm and 6nm filters
The choice between 12nm and 6nm Full-Width-Half-Maximum (FWHM) filters depends on your imaging conditions and camera type. There is no universal "best" option - each FWHM serves a specific purpose.
The 6nm Astronomik Narrowband-Emissionline filters are ideal for imaging faint objects in star-crowded regions of the milky way, as they typically halve the number of stars in the image compared to the 12nm filter. They are also suitable if you have a camera with very low dark current or if you are observing from a location with extreme light pollution.
Difference between Astronomik MFR and MaxFR coating
Both the Astronomik MFR and MaxFR coatings give you the best out-of-band blocking over the entire wavelength range from UV to IR, extremely high contrast, minimized stray light, no halos and needle-sharp stars.
- 6nm MFR-coated filters can be used in all instruments with aperture ratios from f/4 to f/∞ without significant performance loss.
Clip-Filters for Sony Alpha 7 and Alpha 9 cameras
Since 2007, we have offered our extremely popular Astronomik Clip-Filters. The complete range of Astronomik filters is available as Clip-Filters for the Sony Alpha 7 and Alpha 9 cameras.
The Astronomik Clip-Filters offer a number of practical advantages that make them an ideal choice for astrophotographers:
- Installing and removing the Astronomik Clip-Filter is very quick and easy and requires no extra tools or modifications to the camera body. They can be changed at any time, even at night.
- All lens functions, such as focus, aperture, and image stabilization remain fully functional.
- The Astronomik Clip-Filters are held securely in place without stressing the high-quality glass.
- The Astronomik Clip-Filters are designed and optimized for use with both standard camera lenses and telescopes.
Through the Astronomik Clip-Filters, we were able to solve several common issues faced by astrophotographers:
- Large filters for large camera lenses are very expensive.
- Using a filter holder between the camera body and the lens prevents focusing to infinity.
- For very fast telescopes (low f-number) like the Vixen R200SS or the Takahashi "Epsilon" astrograph, a filter drawer or filter wheel cannot be used because the distance to the corrector lenses would be changed.
- Long exposure times lead to dust settling on the camera's sensor chip.
Due to the very tight Sony bayonet and the limited space inside the camera, the Astronomik Sony Alpha 7 Clip-Filters cause a minimal obstruction in the corners. But this can be easily corrected by flatfielding.
Additionally, all Astronomik Sony Alpha 7 Clip-Filters serve as an excellent dust shield, protecting the sensor during long exposures. If you only need a dust shield without filtering effects, the Astronomik MC-Clear Sony Alpha 7 Clip-Filter is the right choice.
Use Astronomik filters for your Sony Alpha 7 or Alpha 9 camera and enjoy marvelous images with ultra-light equipment!
Compatible Sony Alpha Cameras
| Model | Compatibility |
| Sony Alpha 7 | Yes |
| Sony Alpha 7 Mk II | Yes |
| Sony Alpha 7 Mk III | Yes |
| Sony Alpha 7 Mk IV | Yes |
| Sony Alpha 7C | Yes |
| Sony Alpha 7C Mk II | Yes |
| Sony Alpha 7CR | Yes |
| Sony Alpha 7R | Yes |
| Sony Alpha 7R Mk II | Yes |
| Sony Alpha 7R Mk III | Yes |
| Sony Alpha 7R Mk IV | Yes |
| Sony Alpha 7R Mk V | Yes |
| Sony Alpha 7S | Yes |
| Sony Alpha 7S Mk II | Yes |
| Sony Alpha 7S Mk III | Yes |
| Sony Alpha 9 | Yes |
| Sony Alpha 9 Mk II | Yes |
| Sony Alpha 9 Mk III | Yes |
| Sony Alpha 58 | No |
| Sony Alpha 68 | No |
| Sony Alpha 77 (all variants) | No |
| Sony Alpha 99 (all variants) | No |
| Sony Alpha 6000 | No |
| Sony DSLR cameras with A-bayonet | No |
Technical Data
- Guaranteed transmission of more than 90% at both SII lines (671.7nm and 673.0nm)
- Typical transmission of 93% at both SII lines
- Glass thickness: 1mm
- Finely polished optical glass, free of any striae, residual stresses, and bubbles
- Extremely scratch-resistant and durable coating
- Completely resistant against high humidity and aging effects
- Astronomik MFR coating (Astronomik Deep-Sky RGB, UV-IR Block L-1, L-2, L-3, and Narrowband-Emissionline filters)
- Parfocal with other Astronomik filters
- Diffraction-limited
- Optimized spectral windows
- Delivered in a high-quality, long-lasting filter box
Due to the high-precision machining of the carrier substrate, all Astronomik filters are parfocal with wedge errors far below all common tolerances. Astronomik filters are diffraction-limited, ensuring that the optical performance (resolution and contrast) of your telescope is not compromised. Issues concerning focal distances and the exact alignment of images from each color channel are therefore effectively eliminated.
All Astronomik filters are ideal for modern cameras, including both CMOS- and CCD-based models, ensuring you capture the best possible images with your equipment. Sharpness, contrast, and the absence of any reflections and halos are guaranteed. Even with bright stars in the field of view, nebulae and galaxies will be captured with the finest structures.
Every Astronomik filter undergoes a rigorous quality control process before delivery. Additionally, each Astronomik Narrowband-Emissionline filter is measured using a high-end PerkinElmer Spectrophotometer to ensure it meets the specifications published on our website. On the back of each Narrowband-Emissionline filter box, you will find a label detailing the precise spectral data for that specific filter, including the maximum transmission and the recommended range of focal ratios.