About this product
Model: ak_ha-ccd_12nm_31mm
Part Number: 10212331
The Astronomik 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 enormously!
Due to the combination of the narrow bandwidth of 12nm and the high transmission of typically 96% the filter gives you an contrast boost, as all unwanted light from other wavelengths than 656nm is blocked form UV up to the IR. This results in an very dark background compared with any filters with a higher bandwidth
The FWHm of 12nm is optimised for typical DSLR cameras with CMOS sensors and CCD cameras with a normal/high dark current: With these cameras the background signal in images taken from heavily light polluted sites is dominated by the dark current of the sensor, not by flux coming from light pollution. In this case a further reduction of FWHM does not improve the image, as the background will not get darker. Compared to the 6nm filters you have more stars in the field of view which gives you more guiding stars when working with an integrated/dual guiding chip!
Due to the new MFR coating technique you may use one single filter on all instruments up to f/3 without a significant reduction in performance.
The Astronomik H-alpha filter MUST NOT BE USED for solar observation!
FEATURES
- 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): 12nm
- Perfect blocking of unwanted light from UV up to the IR
- MFR Coating technique: Usable with all optics up to f/3
- Optically polished substrate, striae-free and free of residual stresses
- Not sensitive to high humidity or ageing effects
- Scratch-resistance!
- Excellent quality substrate, diffraction limited - the optical performance of your telescope will not be reduced
- Parfocal with other Astronomik filters
- 1mm Glass Thickness
- Supplied in a high-quality, long lasting, filter box
Imaging with Narrowband Filters
If you have to observe from light polluted sites (like most of us...), imaging with narrowband filters is the best way to take great images, as all kind of light pollution can be blocked very effective! Normally 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 with very heavy light pollution or with the full moon high up in the sky!
If you look at other astro-photos, 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!
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 H-alpha line at 656nm.
Tipps and Hints for more applications
Using the H-alpha 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
If want to image faint objects in star-crowded regions of the milky-way, using short focal lengths, the 6nm filter will be the better choice, as the number of stars is reduced by a factor of ~2. You should even take the 6nm version if you have a camera with a low thermal current or if you have to observe from a really heavily light polluted site.
Transmission 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 blue line shows the transmission of the filter.
- The most important emission lines from nebulas are shown in orange. The most important lines are from ionised Hydrogen (H-alpha and H-beta) and double ionised oxygen (OIII).
The major emission lines of artificial 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
Technical Data
- 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): 12nm
- Perfect blocking of unwanted light from UV up to the IR
- Parfocal with all Astronomik filters
- MFR Coating technique: Usable with all optics up to f/3
- Thickness of 1mm
- Not sensitive to moisture, scratch resistant or ageing
- Optically polished substrate, striae-free and free of residual stresses
- Astronomik filters are delivered in a high-quality, long lasting, filter box
Customer reviews
| Average Rating (2 Reviews): | |
Astronomik 12nm H-Alpha Narrowband Clip- Filter 15 February 2021 | Michael
Having just recently bought this filter to use with my Canon 1100D,i was pleasantly surprised at the quality of the Filter,not only that but the Filter comes in its own little protective pouch + protective case.I think thats a nice touch.
Now Astromomik are a well known brand,and are known for the quality of their products.
I was keen to test under a clear sky.
What this Filter does,is that it enables you to take H-Alpha images using a colour camera either with a DSLR or dedicated ccd or cmos.
I have the 12nm Clip Filter that simply just presses into place in front of the Canon sensor.This is very easy to do,and then you are set to go.
It also allows you to take longer exposures,say a few minutes with a DSLR,but longer with a dedicated camera.
I can say that with the 12nm Filter,the results are impressive,showing lots of Ha nebulosity that without this Filter would be very difficult to catch,even with a modded DSLR. I regard this Filter as invaluable when taking deep Ha narrowband images.
I can whole heartedly recommend this Filter for your DSLR or indeed for your dedicated ccd/cmos.
13 February 2019 | Joao
Simple high quality, ty
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