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Imaging the solar corona during eclipse

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#1 rainycityastro

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Posted 23 February 2024 - 01:45 PM

During the previous solar eclipse in 2017, I had 2 imaging rigs, both were attached to full frame 36x24 mm scopes, one was about 900mm FL and the other was closer to 300mm.

I was unable to capture the full corona with the 900mm FL scope but the 300mm was way too large.

 

Based on my understanding, this eclipse will give a much better view of the corona for 2 reasons: -- the sun is closer to the maximum of its 11 year cycle and the moon is closer to us than last time.

 

https://www.space.co...se-april-8-2024

 

I am planning on taking an AP stowaway scope. I will have only one imaging rig. But I have the option of imaging at either 630mm or at 500mm. 

 

1. Which is a better focal length to image at if I wanted to shoot as much of the solar corona as possible? While simultaneously getting the maximum resolution for the prominences, bailey's beads, earth shine etc.

2. What should be the orientation of the camera to get as much of the corona as possible? Basically I want to find the approximate direction of the longest axis of the corona with respect to the celestial poles.

 

Thanks

 

 

 

 

 


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#2 steveward53

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Posted 23 February 2024 - 02:33 PM

Plenty of answers over in the Solar Eclipse section ... smile.gif

 

https://www.cloudyni...r-eclipse-2024/



#3 ch-viladrich

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Posted 23 February 2024 - 03:22 PM

During the previous solar eclipse in 2017, I had 2 imaging rigs, both were attached to full frame 36x24 mm scopes, one was about 900mm FL and the other was closer to 300mm.

I was unable to capture the full corona with the 900mm FL scope but the 300mm was way too large.

 

Based on my understanding, this eclipse will give a much better view of the corona for 2 reasons: -- the sun is closer to the maximum of its 11 year cycle and the moon is closer to us than last time.

 

https://www.space.co...se-april-8-2024

 

I am planning on taking an AP stowaway scope. I will have only one imaging rig. But I have the option of imaging at either 630mm or at 500mm. 

 

1. Which is a better focal length to image at if I wanted to shoot as much of the solar corona as possible? While simultaneously getting the maximum resolution for the prominences, bailey's beads, earth shine etc.

2. What should be the orientation of the camera to get as much of the corona as possible? Basically I want to find the approximate direction of the longest axis of the corona with respect to the celestial poles.

 

Thanks

Both 630 and 500 mm f.l are valid options for 24x36 sensors. In 1998, I used a 440 mm f.l. , and in April I'll use a 600 mm f.l.

 

Going up to 800 mm would also make sense in order to have more resolution.

 

During solar maxima, the corona is symetrical. Have a look here for a current image of the corona :

https://soho.nascom....ealtime/c2/512/

 

This being said, it is way better to align the camera along the east-west axis. This makes processing easier.


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#4 CreatorsHand

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Posted 24 February 2024 - 05:33 PM

During the previous solar eclipse in 2017, I had 2 imaging rigs, both were attached to full frame 36x24 mm scopes, one was about 900mm FL and the other was closer to 300mm.

I was unable to capture the full corona with the 900mm FL scope but the 300mm was way too large.

 

Based on my understanding, this eclipse will give a much better view of the corona for 2 reasons: -- the sun is closer to the maximum of its 11 year cycle and the moon is closer to us than last time.

 

https://www.space.co...se-april-8-2024

 

I am planning on taking an AP stowaway scope. I will have only one imaging rig. But I have the option of imaging at either 630mm or at 500mm. 

 

1. Which is a better focal length to image at if I wanted to shoot as much of the solar corona as possible? While simultaneously getting the maximum resolution for the prominences, bailey's beads, earth shine etc.

2. What should be the orientation of the camera to get as much of the corona as possible? Basically I want to find the approximate direction of the longest axis of the corona with respect to the celestial poles.

 

Thanks

In 2017 I used a Canon 7DII and 500mm f/4L, for a 35mm equivalent focal length of 800mm. I neglected to adjust the camera rotation to align the long axis of the camera frame with the Sun's Equator, but still had room for everything I could pull out of 7 bracketed images between 1/2000 seconds and 2 seconds, f/8, ISO 100, but barely. Another CN member provided an image of the FOV of his Stowaway with FF (644mm) and 6D camera, and I blended that with my 2017 image of totality, rotated so that the long axis of the corona from 2017 was along the short axis of his FOV image, to see how that compared; the FOV was adequate, with some room to spare, so, assuming the Sun is aligned correctly to the camera frame, unless the corona in the N-S direction is larger than the longest streamer I was able to bring out (and special processing could bring out more info) from the 2017 corona, 644mm should be adequate. I plan to use a 92/105FF (the same one as the one for the Stowaway) on my Traveler with a 5DIV, at about 642mm, in addition to the 7DII/500mm f4 I used last time. This will hopefully help you decide; with an APS-C camera and 500mm (which I assume is with a TCC) your FOV would be similar to the first image, and with a 24mm x 36mm sensor camera and FF, it would be similar to the second image. Obviously a 24mm x 36mm sensor camera and Stowaway at 500mm would give a wider FOV yet. I think 644mm (or 630mm, as you mention) would be a good compromise between getting as much corona as possible and getting details in the other areas you mentioned.

 

Paul

 

2017 Totality - Stapleton, Nebraska 7DII/500mm f4

2017 Solar Eclipse-Stapleton.jpg

 

2017 Totality - Matched to Stowaway/6D FOV and rotated

2017 Solar Eclipse-Edit.jpg
 


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#5 rainycityastro

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Posted 24 February 2024 - 07:37 PM

Thanks Paul, this is extremely helpful. I will likely use the Stowaway without the reducer. The only thing that gives me pause is that the corona is supposed to be longer for 2 reasons 1. Closer to solar maximum and 2. Moon is closer so the sky will be darker.

 

Also regarding alignment of the camera - is the long axis of the corona approximately along the sun's equator. I believe it is but looking for more certainty.


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#6 CreatorsHand

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Posted 24 February 2024 - 08:10 PM

Thanks Paul, this is extremely helpful. I will likely use the Stowaway without the reducer. The only thing that gives me pause is that the corona is supposed to be longer for 2 reasons 1. Closer to solar maximum and 2. Moon is closer so the sky will be darker.

 

Also regarding alignment of the camera - is the long axis of the corona approximately along the sun's equator. I believe it is but looking for more certainty.

You are welcome Ram. I've heard the corona will be potentially larger and more uniform, but I haven't heard anyone give a specific prediction by how much. It is my understanding that the longest streamers would be along the Sun's Equator, and they were in 2017. The direction of Solar North (and hence the Sun's Equator) can be determined from Xavier Jubier's eclipse predictions; there will be a red dot on the Sun image that is on the output chart.

 

Paul




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