Sun in H-alpha with basic gear – July 21st
Me having a summer vacation means I finally could find the peace of mind to try to capture the sun from my backyard. First I needed to get me some gear and I managed to borrow:
- Bresser Skylux 7cm apochromatic refractor (a.k.a. “the Lidl scope” because they sold them there a few years ago for little money);
- Coronado SolarMax H-alpha etalon;
- Coronado B600 blocking filter;
- Baader UR/IV cut filter;
- DMK21 mono, Philips Toucam Pro II and a Meade DSI.
So yeah, three webcams. Just to try them out basically. The Meade DSI I eventually did not use because it’s just too old. The DMK21 had my preference but I could not get that one in focus so it had to be the Toucam Pro II. Now, that is an old camera. The previous owner flashed it with SPC990 firmware to get it to work under Windows 10. It’s not a bad camera, but the DMK is simply the better one.
First I had to figure out what imaging software to use with the DMK. WxAstroCapture worked okay but I like FireCapture more so I started with that. That didn’t work so easily and I had no clue as to what settings to use for gain etc. So I asked solar imaging expert Neo from Astroforum.nl who then told me some settings to start with but more importantly he advised me to use IC Capture. So that’s what I did and that’s when I figured out I couldn’t even reach focus with the DMK…
So I had to use the Philips cam and captured some videos on different settings using WxAstroCapture. It’s really hard to get the prominences bright enough and not make the overall image too bright. And if you keep the image dim you can get some nice details on the disk but then you can forget about any prominences on the limb! So getting details on the solar limb and also on the disk is virtually impossible. Or just plain hard, as Neo confirmed after I moaned about that to him ^_^.
Only one video turned out to be good enough to work with. Aligning and stacking didn’t work out well in AutoStakkert!2 (don’t know why and didn’t care for now) so I used Registax 6 for that. I added some wavelets (just tried some stuff) and then used Gimp 2.9 (the 32 bit from Partha) to stretch the levels and apply a high pass filter to get the most detail on the disk. I did however want to see at least something of the prominences on the limb I just overexposed those. You loose some detail in them but you can now get both the features on the disc and the limb in one image. Finally I inverted the image because well… I just like it that way.
Overall, for an old camera like the Toucam Pro II, I am not at all disappointed by the result! I will try again soon and then the DMK will be tried in combination with a barlow lense. Also, I have to focus better because right now the image is quite blurry.