Solar full disc mosaics - ? overlap needed and length of video?

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Radon86
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Solar full disc mosaics - ? overlap needed and length of video?

Post by Radon86 »

Hi All,

[I am not sure which forum this should be put in, so please allocate me in another forum if necessary].

I have been doing some mathematics on optimal number of panes for solar mosaics (for full discs) in H-alpha imaging.
I image with a Quark, so suffer with a relatively small field of view.
Reading Montana's guide, I know I have to move the frames in a horizontal then down, in a zig zag way. If you have not all read her guide, please do so.

I estimate that the:

Solar disc is 1920 arc seconds in diameter.
My FOV of my sensor (ASI174 on my optical system with a 70mm refractor and Quark is: 1332 x 828 arc secs.
I need theoretically about 10 panes to get a full disc (maybe more, maybe less).

1) How much overlap do you need, and is there a best /easiest software to use ?
2) How long should you record for ? Is 500 frames or even 300 frames enough in a video file ?

Here is my theoretical solar mosaic. You start at the top left (blue square) and then move in the direction of the arrows. 10 panes are needed. You end on the 10th pane (yellow square). Is this enough overlap, or do you need about 50 percent overlap on X and Y axis ??

Thanking you all.

Magnus
8-pane-mosaic-v1.jpg
8-pane-mosaic-v1.jpg (114.45 KiB) Viewed 209 times


Solar: H-alpha": Quark Chromosphere filter; Baader white light filters
Scopes: Altair Astro Travel ED70mm (F 420mm, D=70mm);; Skywatcher 90mm (F 910mm D=90mm); GSO focuser;;Altair Astro 60mm guidescope (D=60mm,F=225mm)
Cameras: ASI120mm-S,ASI174mm
Mount: SW HEQ5 Pro, SW EQ3 Pro Synscan (SW = Skywatcher),Vixen Polarie tracker (portable setup)
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Re: Solar full disc mosaics - ? overlap needed and length of video?

Post by Montana »

I would say you have more than enough panes with 8. You seem to have a good amount of overlap. It gets easier if the Sun is very active (lots of alignment point etc). The problem is always in white light when there can be very little to align each panel on. Try it and see :) You will get better with practice.

As for the amount of frames to stack, well that depends on the weather. If the seeing is stable for a long period of time and there are no clouds imminent then you can go for perfection and capture a lot of frames per panel. If time is running short then grab as few as you can get away with. There is nothing worse than completing 7/8 panels :( (been there and done that!). If you have an ASI174 then capturing 1000 frames is only going to take you a few seconds :)

There are plenty of software for blending:
Photoshop Photomerge
Microsoft ICE
I can't remember the name of the one I used to use, hopefully I'll think of it in a minute
https://shotkit.com/photo-stitching-software/
https://fixthephoto.com/best-photo-stit ... tware.html

Alexandra


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Rob63
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Re: Solar full disc mosaics - ? overlap needed and length of video?

Post by Rob63 »

Autostitch is the one I have had most success with, however it is getting on a bit and has not been updated in years.
Only negative is that it can only output as jpeg

Rob.


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Re: Solar full disc mosaics - ? overlap needed and length of video?

Post by marktownley »

Looks like you will be ok with the overlap above. How many frames depends on the seeing - the worse the seeing the more frames!


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