RickS
06-12-2012, 12:24 AM
Here's my final attempt at the solar corona. I promise not to do another repro... honest! ;)
The attached version looks blotchy on my screen which I think is due to the compression that IIS does to uploaded images. The version here probably looks better: http://rickstevenson.smugmug.com/Astro-Photography/Total-Solar-Eclipse-2012/i-kh3TLDZ/0/X3/Corona-v10b-med-X3.jpg
This image was created by stacking 171 subs captured with a Nikon D800E and 70-200mm lens @ 200mm on a fixed tripod at shutter speeds between 1/640 sec and 4/10 sec. Conditions were less than ideal with high cloud and the sun at a low altitude. Processing was done with PixInsight and Photoshop.
A few people have asked for details of the processing, so here's an overview of what I did. I'm not going to give a detailed recipe because I don't have time to write a long essay and also because different data will need different treatment. I'm happy to answer questions if anybody wants to try it...
Processing summary (all steps in PixInsight unless otherwise noted):
My subs were in batches of 9 bracketed images. I registered and summed each batch of bracketed images into a single image using the FFTRegistration script. This registered the images against the moon which is not ideal (the moon and the corona are moving relative to each other) but good enough for short sequences.
I registered the summed images using Photoshop and PixInsight. This step was a bit complicated as I wanted to register against the corona itself. I used the LarsonSekanina filter process to create copies of the first and last summed images with coronal detail. I used Photoshop to register these images (difference layer and manual pixel by pixel tweaking) and calculated how many pixels I had to move the last image in X and Y directions. Using this info and the timestamps in the EXIF data for my images, I calculated the transformation required for each of the intermediate summed images. Then I registered the original summed images in PixInsight using PixelMath to transform each image by the required delta X and Y. This effectively did what a tracking mount would have done automatically and effortlessly :D At the end of this process I summed all the images into a final stacked image.
I used the LarsonSekanina process to bring out the coronal details of the stacked image. Much tweaking of parameters!
Followed by lots of typical PixInsight magic: crop, slight stretch, luminance masked noise reduction, contrast tweaking with HDR Multiscale Transform and Local Histogram Equalization, more noise reduction, some careful sharpening with Multiscale Median Transform and a quick Curves Transformation to adjust brightness and contrast again.
Final steps in PixInsight were to use PixelMath to create a dark blue background and then add a scaled copy of the image to it.
I then exported the image to Photoshop and pasted a nice copy of the moon and prominences over the hole in the middle of the image.
Voila!
I hope that's helpful to somebody... I'd guess I probably spent 30 or 40 hours playing with this. Next eclipse it will be easy so long as I can remember what I did :lol:
Even if you're not interested in the processing I hope you enjoy the image and thanks for looking...
Cheers,
Rick.
The attached version looks blotchy on my screen which I think is due to the compression that IIS does to uploaded images. The version here probably looks better: http://rickstevenson.smugmug.com/Astro-Photography/Total-Solar-Eclipse-2012/i-kh3TLDZ/0/X3/Corona-v10b-med-X3.jpg
This image was created by stacking 171 subs captured with a Nikon D800E and 70-200mm lens @ 200mm on a fixed tripod at shutter speeds between 1/640 sec and 4/10 sec. Conditions were less than ideal with high cloud and the sun at a low altitude. Processing was done with PixInsight and Photoshop.
A few people have asked for details of the processing, so here's an overview of what I did. I'm not going to give a detailed recipe because I don't have time to write a long essay and also because different data will need different treatment. I'm happy to answer questions if anybody wants to try it...
Processing summary (all steps in PixInsight unless otherwise noted):
My subs were in batches of 9 bracketed images. I registered and summed each batch of bracketed images into a single image using the FFTRegistration script. This registered the images against the moon which is not ideal (the moon and the corona are moving relative to each other) but good enough for short sequences.
I registered the summed images using Photoshop and PixInsight. This step was a bit complicated as I wanted to register against the corona itself. I used the LarsonSekanina filter process to create copies of the first and last summed images with coronal detail. I used Photoshop to register these images (difference layer and manual pixel by pixel tweaking) and calculated how many pixels I had to move the last image in X and Y directions. Using this info and the timestamps in the EXIF data for my images, I calculated the transformation required for each of the intermediate summed images. Then I registered the original summed images in PixInsight using PixelMath to transform each image by the required delta X and Y. This effectively did what a tracking mount would have done automatically and effortlessly :D At the end of this process I summed all the images into a final stacked image.
I used the LarsonSekanina process to bring out the coronal details of the stacked image. Much tweaking of parameters!
Followed by lots of typical PixInsight magic: crop, slight stretch, luminance masked noise reduction, contrast tweaking with HDR Multiscale Transform and Local Histogram Equalization, more noise reduction, some careful sharpening with Multiscale Median Transform and a quick Curves Transformation to adjust brightness and contrast again.
Final steps in PixInsight were to use PixelMath to create a dark blue background and then add a scaled copy of the image to it.
I then exported the image to Photoshop and pasted a nice copy of the moon and prominences over the hole in the middle of the image.
Voila!
I hope that's helpful to somebody... I'd guess I probably spent 30 or 40 hours playing with this. Next eclipse it will be easy so long as I can remember what I did :lol:
Even if you're not interested in the processing I hope you enjoy the image and thanks for looking...
Cheers,
Rick.