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My first stab at an HDR image of the sun's corona and lunar Earth-lit side

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#1 Coconuts

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Posted 12 April 2024 - 01:50 PM

I'll use bullets to keep from using overly dense paragraphs.

  • First, a few caveats: My image processing skills are very rudimentary.  I have yet to come up to speed on PixInsight, although I own a copy.  I never learned Photoshop, and discontinued my Creative Cloud subscription since I didn't know enough to use it.  I have managed some passable night-time astro images using AstroPixelProcessor, mostly because it is so easy to use.  I have yet to master the multiple tools needed for solar imaging. 
  • But with 665 partial and heavily bracketed images of the eclipse from our cloud-free site in Quebec, I thought that I should take a stab at the corona and the lunar Earth-lit side. 
  • My scope was an Askar 103 APO (700 mm f/6.8 ED triplet), with a last minute decision to skip the 1.0X field flattener due to concern about lens flares during the diamond ring and Bailey's Beads phases.  700 mm was probably pushing things a bit for a full-frame camera; 600 mm would have avoided clipping any corona.  I knew going in, though, that the corona near solar maximum is much more symmetric; I didn't have to worry about really long east-west streamers.
  • The scope was on an iOptron HAE29EC mount and 40 mm carbon fiber tripod. 
  • I used iPolar and its camera to perform a precise polar alignment the night before, but had to bail on that location in the morning when it became clear that a tree would obscure the final partial phases.  We set up instead in my cousin-in-law's open field, where I set the mount to GOTO the sun, and then adjusted its alt and az to center the sun.  This worked OK, but periodic tweaks with the hand controller were needed to keep the sun in the center of the field.  And yes, I was using the solar tracking rate.  I dug under the turf and set three patio tiles for the tripod leg spikes, since the field was a bit wet from a recent snowstorm melt.
  • The camera was my Ha modded, full-frame Canon 6D, ISO 100.  I thought that the Ha mod would be important to best capture the prominences, but I have since seen great results from unmodded cameras, and a side effect was that my corona images are pink.  I have yet to manage to properly correct that while preserving the prominence colors and getting the lunar details to pop, so the image below is monochrome.
  • There was a Canon right angle finder on the 6D viewfinder, but that was only for framing and rough focus.  For fine focus, I used a 7" HDMI monitor mounted to the camera hot shoe.  With Live View and 10X magnification, I focused as best I could using the large sunspot group.  But it was still tricky.
  • Both the camera and my laptop had substantial external Li-ion battery packs.
  • SETnC automated everything, allowing us to enjoy the visual beauty of the eclipse (multiple AT72EDII's with 12 mm Delos eyepieces, on simple alt-az mounts and tripods, seated in folding chairs).  During totality, my exposure table had fourteen entries, one stop apart, from 1/1000th of a second to eight seconds.  For the HDR image below, I used twelve images, from 1/1000th of a second to two seconds.  I'll also check to see if the mostly saturated four and eight second exposures add anything in the outer parts of the corona.
  • Two individual color images (1/4000th during Bailey's Beads, and 1/4 second during totality, respectively) can be seen here:  https://www.cloudyni...-prominences/. 
  • To process the images, I used easyHDR3 (https://www.easyhdr.com/), which I choose because it looked easy to use.  It is!
  • Upon loading the twelve RAW images, easyHDR created lots of HDR option images to choose among as starting points.  I picked the monochrome one, and then fiddled the tone mapping curve to better bring out both corona details and the Earth-lit side of the moon.  For not knowing what I am doing, I seem to have made a fair bit of progress with very little effort.  The corona structure shows very fine details.  My only edits were to clone away a few small sensor dust motes that were amplified as part of the HDR and tonal mapping processes.
  • The image below is a JPEG, compressed to fit the forum 500KB limit.  The TIFF file is 115 MB.  Enjoy!

HDR twelve image mono.jpg

 

All the best,

 

Kevin


Edited by Coconuts, 12 April 2024 - 01:59 PM.

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#2 rigel123

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Posted 12 April 2024 - 01:56 PM

I'd say that's pretty amazing Kevin!  Those spikes at the 10/11:00 position are what I noticed in my shots that weren't nearly as extensive as you show here but what I would have expected if I hadn't messed up setting the ISO to AUTO! 



#3 gstrumol

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Posted 12 April 2024 - 02:31 PM

Now that's not your typical total eclipse shot! bow.gif waytogo.gif

 

Well done sir ...



#4 XM381

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Posted 12 April 2024 - 10:24 PM

Looks awesome Kevin!

 

I tried several programs but easyHDR3 was easiest to get results I like and recommend it to others trying to process their eclipse pics.

 

I used my Nikon D5300 APS-C with a Nikon 500mm Reflex mirror lens and have shots from 1/4000 to 2 seconds @ ISO 100.

 

Still playing with getting final images but think I have decent data to work with.

 

This is just  easyHDR3, no other processing.

 

HDR A.jpg


Edited by XM381, 12 April 2024 - 10:25 PM.

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