Sun in Ha: 2012-02-20

[NandoPG]

Hi fellows,
Before the afternoon's shower I was able to capture the images below. Seeing was quite unstable, with some moments reaching 2.5/5 and other 1.5/5. Anyway, results below.

Thanks for looking,

Fernando



A huge filaprom on the south limb. Note like the filament still on the disc is connected to the part that is external to the disc.


A large prominence on the SE limb. Judging by its shape, it doesn't look to be a typical quiescent type of prominence


Another large filament. Some fine spicule like structures can be seen


A huge prominence on west limb


Area showing the ARs 11420, 11419 and 11422.
Please check how fast the ARs 11420 and 11419 have been evolving since Feb-18th.

[Cschur]

But such a decent set of images Fernando. The first one looks a bit like Im looking at it through a screen door, but has some very fine details despite the seeing. One suggestion, I have found as has a few others that you can partially overcome bad seeing by taking many more frames in your AVI's, like at least 2000 or more.

[NandoPG]

Hi Chris,
Thanks for the comment and also for the tip, valuable as always.

Tell me if I got that right: normally I capture around 900 frames and use something between 100 and 400 frames for stacking. Your suggestion is to increase the capture to 2000 frames under bad seeing but how many should I use for stacking ?

Thanks again Chris.

Fernando

[MjrTom]

Excellent set of images Fernando
I especially like the first one with the prom still attached to the disc.

[marktownley]

Lovely set of images Fernando!

[swisswalter]

Hi Fernando

very fine shots, especially taking the conditions into account. #3 is my favorite

[Montana]

Wonderful Fernando! especially the first picture, did you take that one when you were passing by on your spaceship?

Regards
Alexandra

[edobosz]

Hi Fernado, well done, good images indeed. I like the second last greyscale prom. I think the issue of how many frames to take initially and then how many to stack is actually quite complex. In poor seeing you want to capture more frames in the hope of striking it lucky with some good frames. In regards to how many of these frames you end up using, this is where it gets tricky. If you have captured the avi with gain turned up it may be noisy, particularly for proms. You will need to stack more of these noisy frames and compromise clarity by including more blurred frames This will allow a cleaner raw image that can then be heavily processed. If you have captured an avi with high signal and superb defintion, then perhaps a few tens of frames is all you need to stack and process for great results. Others in the group may have other thoughts. Ted

[marktownley]

I think the issue of how many frames to take initially and then how many to stack is actually quite complex. In poor seeing you want to capture more frames in the hope of striking it lucky with some good frames. In regards to how many of these frames you end up using, this is where it gets tricky. If you have captured the avi with gain turned up it may be noisy, particularly for proms. You will need to stack more of these noisy frames and compromise clarity by including more blurred frames This will allow a cleaner raw image that can then be heavily processed. If you have captured an avi with high signal and superb defintion, then perhaps a few tens of frames is all you need to stack and process for great results. Others in the group may have other thoughts. Ted

I record 1500 and stack 500 of them...

[NandoPG]

Mjr Tom, Cai-Uso, Mark, Walter, Alexandra and Ted: Thank you so much for your kind remarks and thumbs up on these images. I sincerely appreciated those.

On the issue of the quatity of frames to be stacked, there are two things to be regarded. The level of signal (pixels carrying information) and the level of noise.
The determination of what is noise and what is information is a statiscal process, and as such it is necessary a great number of samples for a good decision. If we were talking about still frames, like it is the case in DSO image processing, the quantity of frames necessary for good statistical decisions would be much smaller than in our solar image processing case, where we have motion - a time variable.
So what I got from Chris tip (please Chris correct me if I am wrong) is that, under a bad seeing, one should capture more frames to generate more samples for decision. But the stacking should be done with a reduced number of frames compared with is used normally. The reason for this is that the quality of the frames decreases very fast in the ranked que and we want to avoid to use those bad frames.

Fernando

[florencior]

Fernando, great images, i prefer the last two. I think under bad seeing is better to avoid long focal length captures. About taking a lot of frames, there are other two facts that should be taken under considetarion, i think:

1. The sun surface and phenomena changes very quickly, so if you are considering capturing many frames you need a very high fps camera, and quick computer and hard disk.
2. There are cameras now that generates very big avi files. I used to capture 1000 frames from which i used about the 100-200 best ones to integrate the final image when i used a DMK21 camera, but now with the Flea3USB3 camera i´ve been pushed to try using less frames; and now i´ve found i get practically similar results if i use 25 frames from a total of 200 captured.