A new solar adventure

Discussions of using SharpCap for Solar or Lunar Imaging
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admin
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A new solar adventure

Post by admin »

Well, the post today brought one of these
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And for once, getting astro equipment delivered did not summon the clouds, so I had a chance to test out the new toy this afternoon. I really feel like I'm at the beginning of a learning curve here - I don't know if the slightly blurry images I am seeing are a result of poor seeing, poor focus or poor tuning of the filter, but I'm sure I will get there given a bit of time. The best feature I could find on the sun was, I think, region 2859
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This was the best 10% of 2000 frames, stacked in AS!2, wavelets in Registax, final tweaks in Affinity photo.

I think I do have an issue with internal reflections, which is showing when I try to expose for any prominences - I see a 'mushroom' shape off the edge of the limb like this
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My best guess so far is that it might be reflections between the base of the Quark and the UV/IR blocking filter that I have on the diagonal, but any other wisdom on this problem is welcome.

cheers,

Robin
Jean-Francois
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Re: A new solar adventure

Post by Jean-Francois »

Hello Robin,

It is each time nice to begin with a new "toy".
Is the filter your first solar equipment ? ... If yes, then it is a good picture.

For the ghost in the protuberance imaging ... that is normal :-) ... the illumination of the full disc is much larger as the rest of the field.
You can may be improve a little bit, if you can put some black material in the tube. Have a look from different side in the tube.
If you see something shiny surfaces, then try to place some black material (if you have access to the place).
If the ghost is produce by not black lenses edges, then it will be more complicated for reducing the ghost (without dismounting your new filter).

For the solar observation ... do you know this project ? http://www.astrosurf.com/solex/sol-ex-p ... on-en.html

I build a Sol'Ex spectrometer and I take regularly images with SharpCap.
I write in SharpCap a small script that start and stop the telescope and the camera with only 1 click and then it starts the film processing.
I can give more information on this project, if you are interested.
For SharpCap new feature ... I have some idea for SharpCap program ... quasi live image processing of the spectrometer film.

Note: it was maybe not raining at your location, but it was raining to the other locations.
Concerning blurry images ... sometimes it is all the possible causes at once.
Do you use the same telescope with other filter ? Herschel prism for continuum ?

Regards,
Jean-Francois

Here a small example what the Sol'Ex spectrometer can do (image from 21.8.) ...
2021-08-21_17_03_33_SolEx.jpg
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Re: A new solar adventure

Post by admin »

Hi,

yes, that was my first time using H-alpha for solar imaging, I have only done white light solar before (and that was a long time ago using an SCT). I had forgotten how hard accurate focus is at high f-ratio. Fortunately the SharpCap contrast range detection tool worked quite well on the detail on the disc for finding best focus.

I had a look at the inside of the tube and could not see anything obvious in the telescope itself, but the base of the Quark eyepiece is bare metal, which could reflect and then back off the UV/IR cut filter. The next time I am out I am going to try loosening the focuser tension screw, which will allow the focuser to droop slightly. If the 'ghost mushroom' moves relative to the sun then I know that the reflections are involving parts of the telescope itself. If the position stays the same then the reflections must be confined to the focuser/filter/diagonal/quark/camera system, which will still be a fixed unit.

I have already had some interesting ideas for new features in SharpCap to help with solar imaging, so overall it was a very positive imaging session.

I will read about the SolEx project - I just had a quick look and it certainly seems interesting!

cheers,

Robin
Jean-Francois
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Re: A new solar adventure

Post by Jean-Francois »

Hello,

Yes, the origin of a ghost reflection can be at several places.
One easy test is without the diagonal or with a different camera.

Also the transmission through the Ha filter device is per construction very low ... only the Ha goes through.
It does not help to have a visual look.
In some cases, it is only possible to solve the problem per iteration ... add somewhere black material and observe, and repeat ...


Regards,
Jean-Francois
eosman
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Re: A new solar adventure

Post by eosman »

Hi
Not sure if your using a tilt adapter to help with Newton Rings.
This could be a light leak around the edge of the adapter...once set I wrap mine in black tape
Hope this helps
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Re: A new solar adventure

Post by admin »

Hi,

no, not using a tilt adapter yet. I still have to find some time to try another session and try to track down the cause of the ghost image. When the sun was shining I was busy, and now we just have cloud cloud cloud :(

cheers,

Robin
eosman
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Re: A new solar adventure

Post by eosman »

Best of luck with locating it Robin hopefully something simple
Heading into the season now of less imaging time and in my case I lose visibility of the Sun in late October early November till late February..and as usual cue more Solar activity
Regards Les
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