Well, it's been a while since I did some imaging (probably since March), with the rainy season here, and the unstable weather at night during the heat wave we currently have in Tokyo (clear weather during the day, cloudy at night). Last night I finally had the weather I needed, and could put to use my SXD2 + Celestron HD800 + 0.7x reducer + 1600MM-C. All of that from my new home, which I just bought in June!
And wow, imaging with an SCT is hard:
- What I feared the most was the guiding performance, but with an OAG, I had a wonderfully flat line, with a total RMS of around 0.4" throughout the night (which I find amazing - in winter I usually get 0.8-1" guiding due to poor seeing).
- Wind was also an issue, but the system was wonderfully tolerant of light to moderate breezes - more and the guiding graph gets all over the place.
- I am using SGP with the Ascom drivers of the ZWO ASI1600MM, as I didn't dare use the native drivers yet. And because the Ascom settings interface seems to have changed (I don't see the offset anymore), I made a mistake and had the gain set to 0 the whole time! When imaging in 3nm narrowband! And I was wondering why I couldn't detach the histogram from the left more, with 10 minute exposures...
- And finally, focusing the thing is almost impossible! I have a Bahtinov Mask I 3D printed, but it is hard to judge when the middle spike is exactly in the middle, and the slightest shift is felt immediately. Plus with temperature shifts, I'm getting the feeling I need to get an auto-focus system there...
Some questions to anyone who has the answer
- How is the SGP support of native ASI1600MM these days? Has it gotten better? And is it prod-ready?
- How to focus an SCT? Would a tri-bahtinov mask work?
- Any suggestion for an autofocus solution for the EdgeHD 800?
- Any idea about that new interface for the Ascom controls of ZWO?
Otherwise, here is the result of the imaging, where I was testing around, 4x180s, 7x240s, 13x600s, at gain 0 (sigh).