H-alpha: This filter is suitable for photographing hydrogen nebulae from areas with light pollution, but also from places with dark skies. The contrasts between objects that glow in H-alpha light and the sky background are greatly enhanced.
Astronomik XT filters for wide-angle lenses: The new Astronomik XT filters have been specially developed for astrophotography with wide-angle lenses and deliver sharp star images right into the corners of the image.
Astronomik clip-on filters have been a popular and well-known accessory for astrophotographers around the world for many years. However, when using lenses with very short focal lengths for wide-angle photography, standard clip-on filters can cause aberrations, and the stars in the outermost corners of the image become streaked. To solve this problem, the new Astronomik XT filters are mounted on an extremely thin substrate with a thickness of only 0.3 mm or 0.5 mm, which significantly reduces these aberrations.
Despite their reduced thickness, Astronomik XT filters offer the highest optical quality: they are finely polished, free of streaks, internal stresses and bubbles, and suitable for the most demanding applications.
Astronomik XT filters are manufactured using the same durable coating technology as all Astronomik filters. They are extremely scratch-resistant, insensitive to high humidity and non-ageing. This ensures that they maintain their performance for years to come.
Please note that not all Astronomik filters are available as XT versions, as the manufacture of these extremely thin filters is very complex. Currently, filters are being produced that are ideal for photography with wide-angle lenses.
Difference between 4nm, 6nm and 12nm filters:
- The 4nm and 6nm narrowband emission line filters are ideal for imaging faint objects in star-rich regions of the Milky Way. They are also recommended if you are using a camera with very low dark current or if you are conducting observations from a location with extreme light pollution.
- The 12nm narrowband emission line filters are designed for use with typical DSLR cameras with CMOS sensors and CCD cameras with normal or high dark current. They are also the preferred choice for cameras with integrated tracking sensors, as they show more guide stars.
In areas with low light pollution, the background signal in the images is usually limited by the dark current of the sensor rather than light pollution. Therefore, further suppression of the sky background by reducing the half-width does not reveal any more details of the object.
Difference between Astronomik MFR and MaxFR coatings (anti-reflective coating)
Both Astronomik MFR and MaxFR coatings offer the best possible blocking across the entire spectral range from UV to IR, extremely high contrast, minimal stray light, no halos and razor-sharp stars.
- 12nm MFR-coated filters can be used in all instruments with aperture ratios from f/3 to f/∞ without any significant loss of performance.
- 6nm MFR-coated filters can be used in all instruments with aperture ratios from f/4 to f/∞ without any significant loss of performance.
- 4nm MFR-coated filters can be used in all instruments with aperture ratios from f/4.5 to f/15 without any significant loss of performance.
The MaxFR coating is designed to work particularly well with very fast optics:
- For 12nm filters with MaxFR coating, this means unrestricted usability from f/1.7 to f/6 and approximately 85% of maximum transmission at f/1.4.
- For 6nm filters with MaxFR coating, this means unrestricted usability from f/2.2 to f/6 and approximately 90% of maximum transmission at f/2.
- 4nm Filter with MaxFR coating are currently in development.
- Filters for even faster optics are available on request.
A bit of help with your selection:
- As a first filter, we recommend the Astronomik CLS filter. This filter suppresses artificial light pollution and natural airglow. By using this filter you get a dark-sky background and can therefore use much longer exposure times to make fainter objects visible. The filter is optimised in such a way that objects are reproduced in their natural colours. Important: the simple CLS filter has no built-in IR-blocking. Therefore you will need the CLS-CCD filter for an astro-modified camera!
- A good choice for working in locations with really heavy light pollution is the Astronomik UHC filter. The transmission curve of this filter only allows the light of the H-beta, OIII, H-alpha and SII lines to pass through. The background suppression is significantly stronger than with the CLS, however this filter works only for gas nebulae! Star clusters and galaxies are largely filtered out.
- For a more in-depth introduction to astrophotography, we recommend the OIII, H-alpha and SII emission lines filters, available with full width at half maximum of 6nm or 12nm. With these filters you can create detailed images of faint objects even from locations with extreme light pollution and a full Moon high above in the sky. Images in these narrow emission lines are not naturally coloured.
- For the owners of astro-modified cameras we offer the Astronomik OWB filter: OWB stands for "original white balance". The filter corrects the displaced colour reproduction of a converted camera so that it can also be used for normal every-day photography, without having to revise every image on the computer.
Model compatibility:
- Sony Alpha 7
- Sony Alpha 7 Mk II
- Sony Alpha 7 Mk III
- Sony Alpha 7 Mk IV
- Sony Alpha 7C
- Sony Alpha 7C Mk II
- Sony Alpha 7CR
- Sony Alpha 7R
- Sony Alpha 7R Mk II
- Sony Alpha 7R Mk III
- Sony Alpha 7R Mk IV
- Sony Alpha 7R Mk V
- Sony Alpha 7S
- Sony Alpha 7S Mk II
- Sony Alpha 7S Mk III
- Sony Alpha 9
- Sony Alpha 9 Mk II
- Sony Alpha 9 Mk III
Not compatible with:
- Sony Alpha 58
- Sony Alpha 68
- Sony Alpha 77 (all variants)
- Sony Alpha 99 (all variants)
- Sony Alpha 6000
- Sony DSLR cameras with A-mount
Due to the very narrow Sony bayonet and the limited space in the camera, the Astronomik Sony Alpha 7 clip filters cause minimal shading in the corners. However, this can be easily corrected by flat fielding.
