The Astronomik OIII filter is ideal for photographing nebulae with oxygen emissions from both light-polluted and dark observation areas. It significantly increases the contrast between objects emitting light at 496nm and 501nm (OIII lines) and the sky background.
The Astronomik oiii filter completely filters out the emission lines of high and low pressure vapour lamps (sodium (Na) and mercury (Hg)), as well as all lines of natural airglow and most of the interfering moonlight.
Photography with Astronomik narrowband filters: Photography with Astronomik narrowband emission line filters is the best method for capturing great images in light-polluted locations, as they effectively block all types of light pollution. An Astronomik h-alpha filter is usually the first filter you need to capture detailed, high-contrast images, even in areas with heavy light pollution or during a full moon. Astronomik h-alpha filters are ideal for capturing all red-glowing nebulae. Astronomik oiii filters expand your possibilities, as they can also be used to capture all greenish and bluish structures that make planetary nebulae, star-forming regions and supernova remnants great targets. If you complete your filter set with Astronomik sii filters, you can use the HSO (H-alpha, SII, OIII) palette to create false-colour emission line images similar to those taken by the Hubble Space Telescope.
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.
