For the last couple of years I've been pretty happy just using my dual narrowband filters (L-extreme, Antlia ALP-T, and IDAS NBZ) to capture various nebula.
At times I would use differing techniques to create an artificial Sii channel to create a simulated SHO image. I had not pursued using my OSC camera to capture Sii due to the fact that a Sii filter will limit the data capture to 1/4 of the sensor. To me, it just seemed somewhat of a waste of the limited imaging time I have in the PNW.
Due to the relatively poor Oiii signal in comparison to the Ha data I capture, one of the tricks I started doing last year was combining the G & B data from images captured with those filters to create a better Oiii channel and subsequently make a nice HOO image. Even still, the Oiii image is typically quite few db's lighter (SNR) than the Ha.
A few weeks ago I found out that Altair Astro (out of the UK-link below) has built a dual narrowband filter that captures Sii and Oiii. I have seen filters that capture Sii and Hb data, but I wasn't sure what I would use the Hb data for as it's still Hydrogen gas emissions and I capture the Ha data very well (probably a little Nii too). At this point, with this new filter I realized I could do my normal capture of Ha/Oiii data and then transition to capturing Sii/Oiii data. Afterwards I could process the data in PI to separate the Ha, Sii, and Oiii signals and build a real SHO image using my OSC camera.
This image is the first test of this process. We're starting to get into the cloudy/rainy season here so I decided to use 13 hrs of Ha/Oiii data on IC1396 that I had previously captured and just add the Sii/Oiii data to that. Since receiving the filter, I've only had one clear night so far and was able to capture almost 6 hours of data. I would prefer about 20 hours but not sure when I'll have more clear nights.
Basic process that I'm using to create the SHO image:
* Separate RGB channels in Ha/Oiii stacked image. Save the G & B channels and rename the R channel Ha.
* Separate RGB channels in Sii/Oiii stacked image. Save the G & B channels and rename the R channel Sii.
* Image integration of all the G & B data to create a new image. Rename new image as Oiii.
* Channel Combination of three channels with R=Sii, G=Ha, B=Oiii.
After adding the Sii data I'm really amazed by the difference it makes in the overall look of the image (previous HOO versions here:
https://www.astrobin.com/zao93h/B/) Unfortunately due to the limited amount of Sii data, I lose a little bit of the fine detail in this new version, but I do like the overall look better.
Link to Altair Astro filter:
https://www.altairastro.com/altair-sii-oiii--dualband-6nm-certified-cmos-filter--test-report-13490-p.aspNote: Shipped to the US there's a warning that there may be taxes and import fees that are due on delivery. Just want to point out that I did not have to pay anything except for the item and shipping.
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