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Astrophotography and Sketching >> Beginning and Intermediate Imaging

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HowardK
Pooh-Bah
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Reged: 10/20/10

Sirius B ......planetary camera and stacking...
      #6391611 - 02/23/14 02:06 AM

Even at around 50 degrees altitude my seeing is always too poor (pickering 4 at best) to see visually Sirius B... with either an 8" Edge or a TEC 140mm.

I tried capturing a few hundred frames of avi's with my planetary ASI 120 colour camera but do not know how best to stack them to bring out the B star.

I use Autostakkert2 or Registax for stacking...can someone give me some tips on how to use these on Sirius?


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StrangeDejavu
Carpal Tunnel
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Reged: 03/20/13

Loc: Florida
Re: Sirius B ......planetary camera and stacking... new [Re: HowardK]
      #6391643 - 02/23/14 02:28 AM

I've not done it myself, but I follow an Italian APer (Giuseppe Donatiello) who does a lot of imaging like this (Sirius B, Rigel B, Procyon B, etc). When I asked about his process, he had this to say:

Quote:

No secret about my method of capture processing of these images. The first stage involves the capture of an AVI movie (30-40 seconds) in a similar way for planetary imaging . For very narrow or unbalanced double stars it is preferable to use long focals of at least 4000 mm ( f/30 or higher, my typical f/45 ). Second stage: processing of the movie. A simple automatic alignment does not produce this result, but an image of confusion which still serve as luminance. Proceeds a second image obtained by extracting individual frames that align manually with excellent RegiStax. This operation is slower and requires a lot of patience: it is not easy to determine what is the optimal alignment in a picture that is very often deformed by seeing. The brain is able to recognize this point better than any algorithm that makes a difference and is perfected with practice. The image obtained is added with the automatic image alignment. At this apply various wavelets, denoise, etc.. If these procedures are been made correctly, you will get an image similar to this one.




Quote can be found here: http://www.astrobin.com/75887/#c31224

Here's some of his work:

Sirius B: http://www.astrobin.com/60905/0/

Rigel B: http://www.astrobin.com/75887/0/

He even discovered an Arcturus B using this method.

Arcturus B: http://www.astrobin.com/73195/C/

Hope this helps.


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james7ca
sage


Reged: 05/21/11

Re: Sirius B ......planetary camera and stacking... new [Re: StrangeDejavu]
      #6391661 - 02/23/14 02:50 AM

Rigel is not particularly difficult. I was able to photograph Rigel A and B with an Astro-Tech AT72ED using afocal projection (equivalent focal length 1032mm at f/14). I also used that same scope to split the double-double in Lyra. I didn't use a video camera, just stills taken with my Sony NEX-5N camera.

I suspect that Sirius would be a more difficult task, probably not possible with my AT72ED. Being an astrophotographer (mainly) I often turn my camera toward double stars and globular clusters when the moon is too bright or if the skies are too hazy to try any other subjects.


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HowardK
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Reged: 10/20/10

Re: Sirius B ......planetary camera and stacking... new [Re: james7ca]
      #6391740 - 02/23/14 05:47 AM

Mitch...thanks

Not sure about "extracting individual frames that align manually".....sounds very tricky.


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KpS
member


Reged: 11/07/09

Loc: Prague, Czech Republic
Re: Sirius B ......planetary camera and stacking... new [Re: HowardK]
      #6408792 - 03/04/14 05:27 AM Attachment (4 downloads)

The image presented here is the first attempt to find out how things are so any calibration of the scale and image orientation are still short. Seeing was variable and rather below average. Sirius at an altitude of 23° above the horizon appeared on the screen as a campfire. Exposition 20 ms I chose so saturated area was under 10" with the hope that such a time captures a star up to tenth magnitude.
North is approximately downwards, the primary focus of C11 is slightly pulled out at about f/11.5, camera ASI120MC. The stack of 4700 images using AutoStakkert.


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HowardK
Pooh-Bah
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Reged: 10/20/10

Re: Sirius B ......planetary camera and stacking... new [Re: KpS]
      #6409941 - 03/04/14 05:39 PM

Can u remember the gain and gamma setting you used Karel?

Can easily see B here

Well done


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KpS
member


Reged: 11/07/09

Loc: Prague, Czech Republic
Re: Sirius B ......planetary camera and stacking... new [Re: HowardK]
      #6410099 - 03/04/14 07:10 PM

FireCapture has a useful logfile. Gain=80, gamma=50. The number 50 means that used gamma is effectively equal to one. Sirius-B was only a few ADU above the background on 16-bit stack and subsequent processing was highly drastic.

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