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My first solar image - 7 Jul


peroni
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Thanks to Bizibilder for a superb tutorial on DSLR solar imaging.

This is my first attempt at solar imaging, taken yesterday between 12:00 and 13:00.

I took a variety of exposures but this picture is a stack of 80 at ISO100, 1/4000 secs exposure.

I cropped the images in PIPP before stacking using Registax 5.1

I managed to use the best 94% of the 80 taken to get 73 shots stacked.

No flat file applied. I did take them but wasn't sure if I could add them to cropped images from PIPP. (Any ideas?)

Wavelet settings were a little less than the values suggested by Bizibilder.

Wave 1 = 52.1

Wave 2 = 26.3

Wave 3 = 14.0

post-15911-0-79539300-1373308128_thumb.j

All comments and advice for improvement welcome :smiley:

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That looks brilliant for a first solar image. I reckon you could back off on the exposure speed a bit and go for more dynamic range, but I'd have been very happy to produce such a good image first time out.

James

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Thanks to everyone for all the great comments...

That looks brilliant for a first solar image. I reckon you could back off on the exposure speed a bit and go for more dynamic range, but I'd have been very happy to produce such a good image first time out.

James

@James, what do you mean by more dynamic range? I have more raw file sets at 1/1000, 1/2500, and 1/3200 (about 80 of each). I could try stacking those and doing some different post processing.

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Let's say each pixel on the camera sensor can record a value of 0 to 255. That is the "dynamic range" of the pixel. Ideally you don't really want to have any pixels reading 255 because they may be overexposed, but it's good to get reasonably close to it because your image willl then contain the widest possible range of colour values and that gives you the largest possible amount of detail.

If you run a set of exposures of 1/1000th and get pixel values from, say, 0 to 200 then you have 201 different colour values in your image. At the same ISO setting a set of exposures at 1/2000th may only have pixel values from 0 to 100, so you've failed to capture as much information to contribute to your final image as you might have done.

You might then think "Ah, I can do a set at 1/800th and get an even larger range of colour values", but of course there are other ssues to deal with too. If the exposure is too slow then seeing can distort the image, for example.

So, the balance is when you get a slow exposure (to give you the maximum range of colour values) that minimises the effects of variation in the seeing. That almost certainly varies with the combination of camera, telescope and film (ND5 or ND3.8, say).

I'd process all the sets you have and see what you think is best. By all means post the results of each exposure time here. I think it would be interesting to compare them.

James

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That's a lovely starter ... :laugh: ... Welcome indeed to the lightside ...

As James suggested , try and keep the original frames looking a little under-exposed rather than getting a "finished" looking exposure.

You can tweak life into a darker image with a little gentle stretching , but a saturated shot can't be retrieved.

I sort out the overall disc first in Reg before Waveletting , I find it easier to tweak the histogram , gamma and contrast without the distraction of the sharper image.

And Wavelets-wise it's a "gently-gently" scenario , depending on the number of frames stacked , the quality of the frames , the camera used , focus , seeing etc , etc the level of sharpening "required" , can differ enormously so I'd be wary of just using the same settings every time.

Generally I'd say less is more in most cases.

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Ok. Thanks to James and Steve for explaining a bit more about the intricacies of this subject.

When I get time I'll process all sets and post here for a comparison.

Sent from my phone :-D

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Thanks Michael. I took 30 flats but wasn't sure how to use them if I cropped the picture in PIPP.

Using PIPP beforehand makes Register processing quicker.

Any ideas?

Do I have to crop after stacking lights and flats?

Sent from my phone :-D

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Thanks Michael. I took 30 flats but wasn't sure how to use them if I cropped the picture in PIPP.

Using PIPP beforehand makes Register processing quicker.

Any ideas?

Do I have to crop after stacking lights and flats?

Sent from my phone :-D

Unfortunately, once you have centred/cropped the images with PIPP you can no longer use calibration frames.

The next version of PIPP will have support for flats, darks and dark flats/bias frames. However, due to the nice weather we are having lately that version is not progressing very quickly!

Great image by the way.

Cheers,

Chris

Edited by cgarry
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The next version of PIPP will have support for flats, darks and dark flats/bias frames.

I'll look forward to seeing that.

With these lovely days we have I'll certainly be taking more shots.

Thought I'd try Backyard EOS next and record a movie with Liveview for stacking.

Beats sitting out in the cold weather late at night :ph34r:

Sent from my phone :-D

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