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Photographic Astronomik Narrowband-Emissionline filter H-alpha with 6nm FWHM and MFR Coating

Astronomik H-alpha CCD 6 nm Filter 1,25" (M28.5)

Astronomik H-alpha CCD 6 nm Filter 1,25" (M28.5)
Astronomik H-alpha CCD 6 nm Filter 2" (E48)
Astronomik H-alpha CCD 6 nm Filter 31mm, unmounted
Astronomik H-alpha CCD 6 nm Filter 36mm, unmounted
Astronomik H-alpha CCD 6 nm Filter 38mm, unmounted
Astronomik H-alpha CCD 6 nm Filter 50mm, unmounted
Astronomik CLS EOS Clip-Filter
Astronomik H-alpha CCD 6 nm Filter SC Rear Cell (2" / 24TPI)
Astronomik H-alpha CCD 6 nm Filter T-Mount (M42x0,75)
Astronomik H-alpha CCD 6 nm Filter Transmission Curve

Click the image for full resolution

Astronomik H-alpha-CCD 6nm Transmission Curve
Astronomik H-alpha-CCD 6nm Transmission Curve

Click the image for full resolution

How to read the chart
  • The horizontal axis is the Wavelength in Nanometers (nm). 400nm is deep blue, at 520nm the human eye senses green and at 600nm red. At 656nm is the famous "H-Alpha" emission line of hydrogen.
  • The transmission in % is plotted on the vertical axis.
  • The red line shows the transmission of the filter.
  • Visual filters: The grey line in the background shows the relative sensitivity of the human eye at night. The maximum is at ~510nm and drops to longer and shorter wavelengths. You can easily see, that you can´t see anything of the H-alpha line at night (even if you can during daylight!) The sensitivity at 656nm is 0% at night!
  • Photographic filters: The grey line in the background shows the sensitivity of a typical CCD sensor.
  • The most important artifical emission lines are shown in orange. The artifical light pollution is dominated by see mercury (Hg) and sodium (Na), which are used in nearly all streetlights.
  • The most important emission lines from nebulas are shown in green. The most important lines are from ionized Hydrogen (H-alpha and H-beta) and double ionized oyxgen (OIII).

The major emission lines of artifical light pollution:
| Hg 435,8nm | Hg 546,1nm | Hg 577,0nm | Hg 578,1nm |
| Na 589,0nm | Na 589,6nm | Na 615,4nm | Na 616,1nm |
The major emission lines of nebulas:
H-β 486,1nm | OIII 495,9nm | OIII 500,7nm | H-α 656,3nm


All  Astronomik Filters are perfect for modern cameras, including both CMOS and CCD based cameras, allowing you to capture the very best images possible with your instruments. Sharpness, contrast and the absence of any reflections is guaranteed.


Each and every Astronomik filter has to pass a complex quality control process before being suitable for delivery to our customers. Each and every emission line filter is measured with a high-end Perkin-Elmer spectral-photometer to make sure that every single filter is up to the specifications published on our website.


On the back of each filter-box you will find a label that details the precise sensitivity and band pass measurements for that individual filter inside the box: You will see the max transmission and the recommended range of focal ratio were the filter will give you the best performance.

This H-alpha Filter is suitable for imaging of Hydrogen nebulas from observation sites with light pollution and from dark sites as well. The contrast between an object glowing at 656nm and the background is increased enormous!

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 656nm 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.

Der Astronomik H-alpha filter MUST NOT BE USED for solar observation!

Technical data of the filter:

  • Guaranteed Transmission of more than 90% at the H-alpha Line (656 nm)
  • Typical Transmission of 96% at the H-alpha Line (656 nm)
  • Full-Width-Half Maximum (FWHM): 6nm
  • perfect blocking of unwanted light from UV up to the IR
  • parfokal with all Astronomik filters
  • MFR Coating technique: Usable with all optics up to f/4
  • Thickness of 1mm
  • Not sensitive to moisture, scratch resistant, not aging
  • opticaly polished substrate, striae-free and free of residual stresses
  • High quality storage box

Imaging with Narrowband-Emissionline 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 kind of light pollution can be blocked very effective! Normaly an H-alpha filter should be your first step into this amazing field of astrophotography! With an Narrowband H-alpha filter you will be able to take deep and contrasty images even wih very heavy light pollution or with the full moon high up 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 your HSO-set of filters. 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. To illustrate this, there are two images shown below: Both were taken with a unmodified Canon 650D. Even as the camera has a sensitivity of less than 10% at H-alpha, there is some signal und structure in the h-alpha image, while you cannot see anything on the image taken with an H-beta filter!

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 and objects glowing at the xx line at xy nm.

Tipps and Hints for more applications:
Using the H-alpha-CCD filter together with OIII-CCD and SII-CCD filters you make produce false-color emission line images (HSO) in the same way as the Hubble-Space telescope. This is possible even from heavyly light polluted sites!

Alternatives:
The lower priced 12nm filters are the right choice for you, if you own a typical DSLR or a CCD camera with a high dark current! The 12nm filters should be the fist choice for cameras with an integrated guiding sensor, as you will have about twice as much stars compared to the 6nm filter.

Filter displayed products below by their features
FWHM
  1. 6nm (37)
Center-Wavelength
  1. H-alpha (656nm) (32)
type
  1. H-alpha (16)

Emission line filter H-alpha 6nm

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