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 Post subject: Solar Imaging Techniques
PostPosted: Fri Aug 16, 2013 8:46 am 
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Joined: Mon Jul 07, 2008 2:43 pm
Posts: 22
Location: London
Hi all,

I am quite new to taking solar time lapse videos and was looking for advice.
Currently I am taking short 500 frame videos every 2 minutes using a lunt 65mm double stacked telescope and my camera is an imagingsource DMK 21AU4 monochrome. I'm stacking them in registax and using after effects to stabilize and process. Does anyone have any tips and tricks? Is 500 frames enough?
Also what is the best camera to use? I have a budget of £500(ish)

So many questions!

Thanks,
Laura :)


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PostPosted: Fri Aug 16, 2013 1:02 pm 
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Joined: Mon Jul 07, 2008 2:43 pm
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Location: London
Ooops 60mm Lunt sorry!


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PostPosted: Sun Aug 18, 2013 11:07 am 
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Joined: Sat Dec 11, 2004 8:18 pm
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Location: Manchester
Dear LauraP
I outlined my own Sun imaging techniques in my 31st July topic "Sun Fun" - so that should give you a good idea of my approach AND MY LIMITATIONS with regards to solar observing\imaging. I have no experience whatsoever with regards time laps imaging so my comments might be rubbish. However, I must say whilst I accept details on the Sun occur very quickly, I'm inclined to wonder if doing time lapse work using the short intervals you might be thinking about (2mins) I suppose you might be thinking of doing it when rapid changes are likely (eg a bright patch is perhaps visually observed to be quickly brightening).
I have some times observed flares myself but not imaged them very often !
When I did I was usually in panic mode !
However, that said if I were thinking of trying to get time lapse images of flares I do think it would make sense to take quite a lot of practice time lapse images beforehand rather than just wait for a potential flare then have a go a time lapse imaging it, without knowing what I was doing (like me now!).
However, another thing that occurs to me is would "2 minutes" be an ideal gap for time lapse imaging say a flare ? From what in my limited experience I've seen flares have no fixed build up, maximum brightness period, size or fade and I haven't the slightest idea what might be a suitable video lapse time to use - I suspect different flares might need different ideal lapse times.
Of course flares may not be the only things you might want to capture.
Over the years I suppose I did quite a lot of CCD imaging both long exposure Deep Sky (single shot Starlight Xpress) and Planetary pics (using cheap cameras like the good old superb) Philips Toucam Pro.
I had also used my Toucam for Sun imaging using Toucam type cameras mid 2000s.
I got my own Coronado 60mm SolarMax just single stacked about 4 years ago. And using it imaged with a Canon 550D-SLR just taking single shots just on a fixed trpod. Nice but eventually decided to go video to get prettier images.
However, I wanted to keep things fairly cheap, easy to set up, fairly compact and light in weight.
I think the 60mm Lunt is probably a superb solar scope. I opted for 60mm Coronado mainly on the basis of cost and my good experiences with my Coronado PST. I suppose cost was the main reason I haven't double stacked - but for now at least single is fine for me. On top of that the Skywatcher AltAz GoTO mount I got in June might be pushed too far with heavier double stacking.
I have always believed (and still do !) that CCDs are better for astronomy than CMOS devices. However, I decided for my (hopefully) pretty Sun pictures a camera a CCD video camera covering the complete Sun disc was needed. So I wanted a biggish sized sensor - your 1\4inch DMK sensor would be too small for me (excellent though I think your camera will be). So I decided on a Opticstar PL-131m monochrome camera - from what I gather no dvantage using a colour camera for the Sun. I think a CCD camera with similar sized Sensor "half inch" would be much more expensive ?
Incidentally I'm told something to be aware of is that sensor sizes are not standardized.
Onee companies 1\2 inch sensor may be slightly bigger OR SMALLER than another company's (and that applies to other sensor sizes too). The stated measurement (diagonally!) apllies to the overall size of the sensors outer plastic frame - not the actual sensor itself !!!?????????
Best wishes from Cliff


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PostPosted: Sun Aug 18, 2013 12:05 pm 
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Joined: Sat Dec 11, 2004 8:18 pm
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Location: Manchester
Dear LauraP
Just after I posted my recent reply to you I then saw Smerral's superb 14th August images.
He will probably give you much better advice than anything I can provide.
However, there is one thing I forgot to mention.
You said you take about 500 frame individual imaging clips. Well when I got my new PL-131m video camera I was quite surprised when Opticstar suggested taking about 200 frame video clips of the Sun - when I was imaging planets using the old Toucam I usually took clips of 1,000 frames or more, sometimes more than 2,000 (2,000 being the most Registax would handle.
I find in practice that Registax 5 will only handle a few hundred PL-131m video frames at most. took me by surprise at first until I thought it was likely because the PL-131 1\2inch sensor is much bigger than the Toucam 1\4 inch (?).
Another "problem" I find is that although I might take a 20 second video clip possibly supposed up to 400 frames- I actually capture less! I gather that might be because I now use a battery powered laptop to capture images, rather than connected to indoors mains PC as when Toucamming in the old days- and the battery laptop might not provide sufficient power to capture all the supposed 20 fps of my PL-131m.
It occurs to me if you use a battery powered laptop you might not be able to use a video to capture at flat-out frame rate ?????
Best wishes from Cliff


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PostPosted: Sun Aug 18, 2013 12:50 pm 
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Location: Caithness
Hi Laura,

I'm afraid I don't know a lot about time lapse photography either (probably as I have an alt-az mount which would show field rotation) Are you a member of Solar chat (http://solarchat.solarastronomy.org/index.php/en/). I'm sure if you asked your question there people would only be too happy to help. :)

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BRIAN
Celestron Nexstar 8SE
Altair Astro 102 ED refractor with Lunt B600 CaK diagonal
Coronado PST DS, Daystar Quark
ZWO ASI120MM camera, Canon 1000D (astro modified)
Gallery: http://www.astrobin.com/users/smerral/


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PostPosted: Tue Nov 19, 2013 10:08 am 
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Joined: Mon Jul 07, 2008 2:43 pm
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Thanks so much for the very concise answers, I will hopefully put this to practice on the weekend!

I will try to experiment with the amount I capture and post the results. I never even took into consideration the movement of sun flares so I will experiment.

Cheers guys :)
Laura


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PostPosted: Tue Jan 21, 2014 10:14 am 
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Joined: Tue Dec 31, 2013 9:06 am
Posts: 43
Hi Laura,

I can offer some quite comprehensive advice on solar imaging if you still need it. Took me a while to get some acceptable results (http://www.flickr.com/photos/30649972@N ... 4/sizes/o/)

Happy to pass on what I did to get this if it would help. The above image was taken using a Lunt LS60 along with a DMK 21AU618 mono camera.

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TMB152;Tak TOA150/FSQ106ED;Lunt LS152T/LS60THa;Orion 16" Dobsonian;Meade 14" LX200GPS
Canon 5DmkIII;DMK 21AU618;ASI 120M
AP 1200GTO;EQ6 Pro


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