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Solar Imaging 101 with Daystar Scout SS60 Ha, ZWO ASI183MC and GIMP / iPhone. A solar astrophotography beginner's findings. What can you add?


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Here's a summary of some lessons I've learned, following an earlier topic in which two experienced members kindly gave some of their hard earned advice (the topic's linked here and called "Disc and prominence - Daystar Scout SS60-DS 17th March 2021 from Cornwall, UK (plus a request for your help please"):

I've a reasonable amount of dark / night time astronomy and limited experience with a decent astrophoto camera (but only within the past few months moved to the ASI183MC from an SLR), so some of the below may be obvious to anyone with a modicum of experience, plus of course has parallels with dark astrophotography, but I thought worth noting here in case it's of help to you too.

  1. Timing - mid morning's good: when the sun's not yet created a heat haze in the atmosphere, but is still high enough above the horizon not to have too much atmosphere's to look through (just like night time astrophotgraphy).
  2. Seeing makes a big difference - just as at night, look out for high haze and turbulence
  3. Focus remains important, but finding it is easier than at night
  4. Use Firecap or Sharpcap, instead of ASI Studio
  5. Don't use AVI video: using .SER files correlated with better results for me (and plain still captures didn't yield the best results either)
  6. Keep exposures short (with this setup showing most of the disk, but not quite all, mine typically 35-40ms for surface and 70-90ms to give more prominence detail)
  7. Set Gain low (I leave at zero / 0 for now)
  8. I set Gamma at 50, but don't know what others use
  9. I've yet to determine the best video length - experienced people talk of 1000 frames, but I think I've used about 500 so far, over about 30-60 seconds of capture). Wish I'd captuured the screen, to show you.
  10. Be selective - use a small portion of your video frames. I've been using 10%-25% when seeing is good, experienced members have recommended <10% for better quality
  11. Autostakkert select Surface mode (because the whole disc doesn't quite fit in with this camera / scope combination). If a new camera / setup allows whole disc it'll be
  12. approximate polar alignment is OK for videos, don't let the disc drift to the edge of the fram
  13. When getting Autostakkert alignment, set AP size to 104 or 200
  14. I need to learn GIMP. Use Colour > Levels (to stretch, in a similar way to DSO work) is useful, as is the Brightness / Contrast settings plus, as here, crudely joining two images of proms and surface layers.
  15. In the interim, the iPhone adjustments can give a pleasing result - here I've increased saturation and contrast more easily than I find in Photoshop or GIMP.
  16. I've yet to work out how to debayer properly, to get rid of the square artefacts.

Result attached: a very crude two layer (not blended, just placed) with the background image exposed for prominences, the top layer plonked on with surface detail. Minimal processing in GIMP and iPhone. Also the prominences were a little overexposed, but I wanted to yank out some of the shapes quickly and easily. Other results with lower exposures, pushed harder, have yielded better prominence detail overall.

What can you add to this list, to help others?

 

Solar 2 layer prominence and surface 17th April 2021 Daystar Scout.jpg

AutoStakkert settings.png

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Ad 5): AVI format only supports 8 bit resolution, with SER you can get up to 16 bit.

Ad 6): just fill your histogram up to about 90%. The prominences will appear once stretching (see my point 17 below)

Ad 7) and 8): I use the standard settings for my ZWO ASI174MM, they work fine for me.

Ad 9): I usually limit the video to 120s. The Sun is quite dynamic, longer exposures may smear detail.

Ad 16): best to use a monochrome camera, which provides more detail at the same pixel size.

17): Try using IMPPG for processing the prominences.

Nicolàs

PS: attached the Sun of last Sunday (Lunt LS80THA single stack, ZWO ASi174MM)

1112146658_ZWOASI174MM_210411_154527_AS_P25_lapl5_ap49imppg.jpg.65c07a450bf88f8937b900f9255e2f21.jpg

Edited by inFINNity Deck
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