The Askar 6nm Duo-narrowband D1 and D2 Filters (Ha/OIII & OIII/SII) have ultra-high transmittance over 90% of their centre wavelengths and can effectively eliminate the influence of light pollution.
Even in locations seriously affected by light pollution, images made with the Askar 6nm Duo-narrowband Filters are still of very high quality.
The Askar 6nm D1 and D2 Duo-narrowband Filters are ideal for photographing emission nebulae, planetary nebulae or supernova remnants.
The narrow bandwidth of these filters effectively blocks out the effects of light pollution or other distracting factors such as night glow.
Currently available as a 2" Mounted filter set (other sizes planned).
Colour Magic 6nm Duo-narrowband Filters (Ha/OIII D1 and OIII/SII D2)
While most of the commercially available duo-narrowband filters for deep-sky astrophotography are in the Ha and OIII bands, ASKAR offers another structure in addition to the Ha/OIII : SII & OIII.
When shooting deep-sky galaxies with colour cameras, a duo-narrowband filter in the Ha and OIII bands is often used; whereas with a mono camera, a narrowband filter in the Ha, SII and OIII bands is often used, leaving users with colour cameras missing one band of nebula detail. This can be compensated by using the SII and OIII D2 duo-narrowband filters mentioned above.
The Askar 6nm Duo-narrowband Filters use ultra-high transmittance over 90% at their centre wavelengths. The Askar 6nm Duo-narrowband Filters can effectively eliminate the influence of light pollution. Even if you are in an area seriously affected by light pollution, the pictures taken with the Askar 6nm Duo-narrowband Filter Sets are still of very good. quality. It is so practical and efficient that you can get astronomical images of high quality with just two duo-narrowband filters (D1 and D2) and an ordinary astronomical colour camera.
The Askar 6nm Duo-narrowband Filter Set is ideal for photographing emission nebulae, planetary nebulae or supernova remnants, and have very high transmittance at their central wavelengths. The narrow bandwidth of the filters effectively block out the effects of light pollution or other distracting factors such as night glow.
Specifications D1
- 6nm Duo-narrowband Filter (OIII & Ha) 2”
- FWHM: 6nm
- CWL: 500.7nm & 656.3nm
- Peak transmittance：90%
- Thickness：1.85 ± 0.05mm
- Barrier property：≥OD5 @ 200-1100nm
- Surface finish：60/40
- Parallelism：30”
Specifications D2
- 6nm Duo-narrowband Filter (OIII & SII) 2”
- FWHM: 6nm
- CWL: 500.7nm & 671nm
- Peak transmittance：90%
- Thickness：1.85 ± 0.05mm
- Barrier property：≥OD5 @ 200-1100nm
- Surface finish：60/40
- Parallelism：30”
Further Notes
When shooting data through both dual band filters (D1 and D2) and a colour camera, users will have remarkable results.
Usually, in astrophotography, the Hα signal-to-noise ratio is stronger while the OIII is relatively weak. As our two duo-narrowband filters are Hα+OIII and SII+OIII, the combination can balance the signal-to-noise ratio of each channel when shooting data, and after image processing, it can achieve an excellent result which is almost as good as shooting with a combination of three narrowband filters and a mono camera.
Askar have named the Hα+OIII 2" 6nm duo-narrowband filter "D1" and the SII+OIII filter "D2". They are now available as a set in 2" Mounted format only.
Here is a link detailing how to process D1 and D2 Data in Pixinsight
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