2017 Solar Eclipse - Corona

[Alejandro Tombolini]

Hi, a little late but we finally manage to have an image.

The HDR was truly a challenge, we did several approaches without success until we find the way.
The individual images were splitted in R, G and B channels and each of them were composed in two different batches, one with five images (the longest exposures) and the resulting partial HDR with the rest of the shortest exposures. This way we found adequate parameters to compose the images without lowering too much the binarizing threshold.

The moon was manually aligned with crop tool and added through a circular mask. It is almost not processed.
We decided not to increase saturation and contrast in the prominences and let them little noticeable and according to the bright of the Corona.   

We also deal with some noise near the disc because we had a fewer images of short exposure. (The long exposure image is an integration of 15 images and the rest of shortest exposure images are integration of 6 images.)

Saludos,
Alejandro.



More information of the image here.

[pfile]

very nice. the contrast in the corona is great.

if i understand what you wrote there are not too many subexposures here? one problem i had is that i used all of my exposures and of course the moon moved across the face of the sun during the duration, leaving kind of an elliptical "hole" where the moon was. it seems that perhaps i should have just taken one exposure ramp and used that but based perhaps on deep sky image processing biases i felt i should use all 3 ramps i had.

i think the splitting of RGB is very important because the saturation points in the R vs G and B channels turned out to be very different.

rob

[Luigi]

Wow that is excellent. Reminds me to get back to my eclipse HDR processing.

I have two ramps but have created an image using only one ramp. I did exposures up to 6 seconds but they were washed out. I used my modded D610 and an 80mm f/7 scope and I'm not seeing the stars you have .. (maybe one or two and they are trailed because I had my mount on solar tracking)

[Alejandro Tombolini]

Thank you Luigi and rob!

if i understand what you wrote there are not too many subexposures here?

Yes, there are many sub exposures. In total there are 11 image in the HDR and each of them is an integration of 6 (maximum for combination and no rejection in the integration), except the longest exposure that is an integration of 15 images.
The list is:
10 x 6 x (1/800, 1/400, 1/200, 1/100, 1/50, 1/25, 1/13, 1/6, 1/3, 1/1.6) seconds ISO 800 and 1 x 15 x 1.3 seconds ISO 800. The order of the exposures was alternated in the acquisition program.

i think the splitting of RGB is very important because the saturation points in the R vs G and B channels turned out to be very different.

I agree, we couldn't make any good approach with the RGB integrations. We separate the channels and had issues mainly with the green channel, I don't know exactly why but once I found the parameters for red channel, I almost repeated the same values in blue channel but it was completely different in green. 

Saludos, Alejandro.