Astronomik Hydrogen-Alpha / H-a 12nm Imaging Filter - 31mm Round Unmounted
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The Astronomik H-alpha filter is ideal for imaging hydrogen nebulae from both light-polluted and dark observation sites. It significantly enhances the contrast between objects emitting light at 656nm (H-alpha line) and the sky background. The Astronomik H-alpha 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.
With a narrow bandwidth of either 12nm or 6nm and high transmission rates, the filter effectively blocks all unwanted light from wavelengths other than 656nm from ultraviolet (UV) to infrared (IR).
The Astronomik H-alpha filter MUST NOT BE USED for solar observation!
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 12nm Astronomik Narrowband-Emissionline filters are better suited for use with typical DSLR cameras with CMOS sensors and CCD cameras with normal or high dark current or if you are observing from suburban or dark-sky locations. They are also the preferred choice for cameras with an integrated or dual guiding sensor, as they generally show more guiding stars compared to the 6nm filter.
In areas with little light pollution, the background signal in images is usually limited by the sensor's dark current rather than light pollution. Therefore, further suppression of the sky background by reduction of the FWHM does not bring out more details in the object.
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.
- 12nm MFR-coated filters can be used in all instruments with aperture ratios from f/3 to f/? without significant performance loss.
Size of filter
Astronomik filters come in a wide range of standard sizes, both mounted and unmounted, to suit various optical setups and cameras.
This filter is a filter with a protective ring for filter wheels without screw thread. The glass thickness is 1mm, the mechanical thickness is 3mm, the diameter is 31mm.
Technical Data
- Guaranteed transmission of more than 90% at the H-alpha line (656nm)
- Typical transmission of 96% at the H-alpha line
- Glass thickness: 1mm (except Astronomik OWB Type 3 and XT filters)
- 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. The Astronomik MFR coating is designed for optimal performance across a wide range of focal ratios of the optics used.
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.
| Free Shipping Graphic | Free US Shipping |
|---|---|
| Hide Found a better Shipped Price on Frontend? | No |
The Astronomik H-alpha filter is ideal for imaging hydrogen nebulae from both light-polluted and dark observation sites. It significantly enhances the contrast between objects emitting light at 656nm (H-alpha line) and the sky background. The Astronomik H-alpha 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.
With a narrow bandwidth of either 12nm or 6nm and high transmission rates, the filter effectively blocks all unwanted light from wavelengths other than 656nm from ultraviolet (UV) to infrared (IR).
The Astronomik H-alpha filter MUST NOT BE USED for solar observation!
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 12nm Astronomik Narrowband-Emissionline filters are better suited for use with typical DSLR cameras with CMOS sensors and CCD cameras with normal or high dark current or if you are observing from suburban or dark-sky locations. They are also the preferred choice for cameras with an integrated or dual guiding sensor, as they generally show more guiding stars compared to the 6nm filter.
In areas with little light pollution, the background signal in images is usually limited by the sensor's dark current rather than light pollution. Therefore, further suppression of the sky background by reduction of the FWHM does not bring out more details in the object.
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.
- 12nm MFR-coated filters can be used in all instruments with aperture ratios from f/3 to f/? without significant performance loss.
Size of filter
Astronomik filters come in a wide range of standard sizes, both mounted and unmounted, to suit various optical setups and cameras.
This filter is a filter with a protective ring for filter wheels without screw thread. The glass thickness is 1mm, the mechanical thickness is 3mm, the diameter is 31mm.
Technical Data
- Guaranteed transmission of more than 90% at the H-alpha line (656nm)
- Typical transmission of 96% at the H-alpha line
- Glass thickness: 1mm (except Astronomik OWB Type 3 and XT filters)
- 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. The Astronomik MFR coating is designed for optimal performance across a wide range of focal ratios of the optics used.
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.
| Free Shipping Graphic | Free US Shipping |
|---|---|
| Hide Found a better Shipped Price on Frontend? | No |
Astronomik Hydrogen-Alpha / H-a 12nm Imaging Filter - 31mm Round Unmounted