Halpha sun of May 8th

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stef41
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Halpha sun of May 8th

Post by stef41 » Tue May 08, 2018 1:54 pm

Good morning, everyone,

a thunderstorm front sun with the fs60 equipped with its sm40 double stack, glasspath x1.25, BF10 and zwo178mm around 08h45 UT

Image

Image

to powermate x2.5 (50% with a flat that does what it can...)

Image

Sincerely,
stéphane - France

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eroel
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Re: Halpha sun of May 8th

Post by eroel » Tue May 08, 2018 4:17 pm

Stephane:
Nice session.
Best regards,
Eric.

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Re: Halpha sun of May 8th

Post by rsfoto » Tue May 08, 2018 4:43 pm

Great Images and the Sun is not that or dead :-) quiet

What a pity about the Newton rings
regards Rainer

Observatorio Real de 14 San Luis Potosi Mexico

Bruce Girrell
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Re: Halpha sun of May 8th

Post by Bruce Girrell » Tue May 08, 2018 5:04 pm

Stéphane

You might want to try Mark Townley's trick of applying a heavily median filtered version of the image to act as a flat. He has videos on his site.

Basically the process involves making a duplicate layer in Photoshop, then applying a heavy median filter to the image. What you want to do is make the radius of the median filter larger than any image detail but smaller than the width of the rings (in pixels). In Mark's video, he mentions that he uses a radius of 70 as a starting point for his images, but that the radius is dependent on your particular image. You then change the blending mode of the layer to Difference, at which point the screen will go mostly black. Use the Curves adjustment to adjust the shape of the tone curve for your median filtered layer. As you pull the curve downward, your image will become brighter and the detail will begin to emerge. It is then a bit of a balancing act to get the right balance in the image. Mark uses the Darken preset in the Curves adjustment and demonstrates that in his video. I like to adjust the tone curve more directly. To each his own.

When you get the image balanced out, it will still be rather dark. Flatten the image and then use Curves again to restore the brightness range in the image that you want.

I applied Mark's method to your image. I reverted to monochrome, because the method works easier at that point in the workflow. The point at which you set the Difference mode can cause problems with colored images. Based on the size of your image, I ended up using a median radius on 20. This is a low number, but your rings are closely spaced and I had to keep the median radius low so I that I didn't wipe them out. Here is what the median filtered image looks like
S20180508-09h02UT-sm40DS-fs60-gpx1.25-bf10-bx2.5-asi178mm-r50Median filtered.jpg
S20180508-09h02UT-sm40DS-fs60-gpx1.25-bf10-bx2.5-asi178mm-r50Median filtered.jpg (272.74 KiB) Viewed 487 times
I would like to use a larger median radius because what you really want to do is wipe out all of the detail in the disk leaving only the rings. As you can see, there is a good bit of the larger features remaining in the filtered image. You can use the Healing Brush to paint in a more representative shade.
S20180508-09h02UT-sm40DS-fs60-gpx1.25-bf10-bx2.5-asi178mm-r50Median filtered patched.jpg
S20180508-09h02UT-sm40DS-fs60-gpx1.25-bf10-bx2.5-asi178mm-r50Median filtered patched.jpg (274.07 KiB) Viewed 487 times
Don't be afraid to smooth out the light and dark areas more than I did. You want this image to be the best representation of the rings possible.

After changing the mode to Difference, flattening the image and restoring contrast, this is what I got
S20180508-09h02UT-sm40DS-fs60-gpx1.25-bf10-bx2.5-asi178mm-r50 with median.jpg
S20180508-09h02UT-sm40DS-fs60-gpx1.25-bf10-bx2.5-asi178mm-r50 with median.jpg (948.39 KiB) Viewed 487 times
There are still some traces of the rings, but the severity has been greatly reduced. Note also that the brightness across the face of the disk has also been flattened. This can be advantageous if your etalon has a hot spot, but if you want the brightness to vary as it did in the original, then it's just a couple more steps in Photoshop

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Re: Halpha sun of May 8th

Post by Carbon60 » Wed May 09, 2018 7:13 am

Nice images, Stephane.

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Re: Halpha sun of May 8th

Post by Montana » Wed May 09, 2018 12:07 pm

Absolutely wonderful detail in these images :bow and the Mark T method is the way to go with the rings :)

Alexandra

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Re: Halpha sun of May 8th

Post by robert » Wed May 09, 2018 12:34 pm

I have had newton rings using a barlow lens. When I tried a different make they went away.
Also I use a tilt adapter on the LS60 which had problems with rings. I suggest trying something other than the televue and also a tilt adapter.

Good luck
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Re: Halpha sun of May 8th

Post by marktownley » Sun May 13, 2018 1:18 pm

Top shots!
Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!

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