Getting a full disk image

Use this section to discuss "standard" Baader/Coronado/ Lunt SolarView/ Daystar, etc… filters, cameras and scopes. No mods, just questions/ answers and reviews.
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TotalityTown
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Getting a full disk image

Post by TotalityTown » Wed Dec 06, 2017 4:05 pm

Greetings, Everyone.

I'm brand new here and just beginning my adventures into solar imaging for myself (I was part of someone else's project for the solar eclipse back in August).

My goal is to get whole-disk images of the Sun and Moon, respectively. I know that comes either from making a composite image or from having the right camera for your telescope. Eventually I will be able to justify a new CCD, but right now I am trying to learn with my Orion StarShoot webcam and an old Meade DSI. How can you determine whether or not the entire Sun will fit in an image? I found a few equations which I thought would help me get there, but the sun still did not quite fit when I tried the cameras out on a few borrowed telescopes which I thought would have worked.

I appreciate and help and guidance I can get!

Zack

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robert
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Re: Getting a full disk image

Post by robert » Wed Dec 06, 2017 8:06 pm

You could use this field of view calculator
http://m.skyatnightmagazine.com/astrono ... calculator

Focal reducers can be used to shrink the disk and are not expensive too.
Robert
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robert
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Re: Getting a full disk image

Post by robert » Wed Dec 06, 2017 8:11 pm

images and animations http://tinyurl.com/h5bgoso
2017 images http://tinyurl.com/gvk9k3k
2016 images http://tinyurl.com/hfhwnwl
ED80. SW200. ES127. Celestron-150mm-PST mod
LS60PT-LS60F-B1200. B600-Cak. PGR-Ch3-IMX265

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Bob Yoesle
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Re: Getting a full disk image

Post by Bob Yoesle » Thu Dec 07, 2017 8:36 am

Multiply the focal length by 0.0092 to get the average solar disc diameter at focus.

Example 1000 mm FL x 0.0092 = 9.2 mm image diameter.
You'll have to add a bit to this to allow for capturing prominences around the disc periphery.

sensor-size-comparison.jpg
sensor-size-comparison.jpg (44 KiB) Viewed 112 times

As you can see this would require quite a large and expensive camera sensor. Using a smaller chip with very small pixels and a shorter focal length would be a good idea, or using mosaics to build up a full disc image.
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TotalityTown
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Re: Getting a full disk image

Post by TotalityTown » Thu Dec 07, 2017 6:52 pm

Perfect, that's exactly the type of help I was hoping for. I'll re-run my calculations and look up the specs on my DSI again. I know I'll eventually probably end up getting a refractor that is not an h-alpha. Now I'll be able ot make sure I get one with the appropriate focal length. Thanks!

Zack

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