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SteveBz

Solar flats

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Hi Guys, 

Does anyone use solar flats to flatten their solar images? I'm guessing now would be the time to make them. 

Do you have a complete workflow? 

Regards, 

Steve. 

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Defocus whilst on a plain section (easy to find these days!!) of the sun surface , take a 5-10 sec AVI, stack in AS!3 to produce a master flat. Job done.

You may be better off putting this in the imaging section!

Edited by Freddie
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22 minutes ago, Freddie said:

Defocus whilst on a plain section (easy to find these days!!) of the sun surface , take a 5-10 sec AVI, stack in AS!3 to produce a master flat. Job done.

You may be better off putting this in the imaging section!

I was thinking that you'd be better off averaging over a number of days to avoid the natural granularity of the sun becoming a factor. Is that not necessary? 

Regards

Steve. 

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25 minutes ago, Freddie said:

Defocus whilst on a plain section (easy to find these days!!) of the sun surface , take a 5-10 sec AVI, stack in AS!3 to produce a master flat. Job done.

You may be better off putting this in the imaging section!

Should I repost in imaging? Maybe one of the admins can move it. 

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2 hours ago, SteveBz said:

I was thinking that you'd be better off averaging over a number of days to avoid the natural granularity of the sun becoming a factor. Is that not necessary? 

Regards

Steve. 

No, the defocus removes any detail.

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2 hours ago, Freddie said:

No, the defocus removes any detail.

OK, tx. I'll test it out. 

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Using Firecapture allows the user to take a flat before the imaging run and apply it as the data is captured.

The method is very simple, especially for the mosaics i do. I defocus, set the histogram to 50-70%, capture flat field. When you capture your data the flat is automatically applied. You have do a new flat whenever the imaging train is altered.

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I can fit the full disc on my 178MC, but cant get flats with it.  Defocusing doesn't work, and a thin sandwich bag blocks out all the light.  Any suggestions?

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I was thinking of averaging over several days so that rotation of the sun removed any granulation. In the meantime you could download some from nasa/soho, after all, a sphere is a sphere is a sphere. But you might have to do something about aligning histograms - maybe. I haven't done any of this yet, but here's a flattened picture from soho. 

image1573037998164.thumb.png.2cecc0fbbb01551e24235cce7f238e81.png

Additionally, I'd quite like to stretch the histogram from the top creating greater contrast and uncurl it by dividing by sin(theta) so that the edge artifacts  don't look edge on. 

Good luck,

Steve

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