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Author Topic: Widefield Solar Imaging using DSLR  (Read 3317 times)
chrishet
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« on: May 13, 2012, 07:24:30 PM »
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Hi all,  my first post here...a great admirer of Michael's for years...years...years...and this site has meant a lot to my career for sure.

I am an avid astrophotographer and have a bit of experience in solar photography using an Ha solar scope.  I will be heading west to photograph next weeks annular solar eclipse...I will be in Chico CA.  I'll be imaging the event using my solar scope but I also want to get some landscape shots with the setting/eclipsing sun.  Given I only have 2 hands, and the Ha scope will take my full attention, I was planning on setting up a remote camera with a widefiled lens and an intervalometer (TC-80N) to fire off shots every few minutes during the event - with the setting sun and some foreground subjects.  I am fearful of the effects shooting the sun direct will have on my sensor (Canon 7D or 40D).  I am looking for any special precautions that I should do to protect the camera...thoughts?

Thanks in advance!
Chris
ImagingTheCosmos.com
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Fine_Art
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« Reply #1 on: May 13, 2012, 10:18:56 PM »
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Contact the manufacturer for their advice? Discussion on a forum is one thing, advice that can damage or save your equipment is probably best left to someone that has coverage for liability if they make a mistake.

I expect a wide lens to be just like a magnifying glass to the sun. If my understanding is correct it will do more damage to your sensor than a telephoto lens of the sun. The lens diameter is focused to a tiny spot which could burn the equipment faster that a big zoomed sun spread over the sensor.

When it is eclipsed is fine, what do you do for protection before and after? Especially remotely.
« Last Edit: May 13, 2012, 10:34:49 PM by Fine_Art » Logged
PierreVandevenne
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« Reply #2 on: May 14, 2012, 03:10:37 AM »
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Hi Chris,

Given your equipment and the images your have produced, I am surprised you are the one asking fort advice :-) I am sure you know most people would go for astrosolar sheets, but of course, they would essentially drop the background doing so.

I wouldn't worry too much with a wide angle lens and if not tracking. People accidentally put the sun in wide field images all the time and, unless the shutter is wide open for relatively long exposures, nothing bad happens. I've done quite a few time lapse videos where the sun appeared from behind clouds and the cameras used haven't suffered. It's a bit different if you are tracking the sun because there will be some heat buildup at the shutter especially if you keep the mirror up. But if the sun is low on the horizon, this is not an issue.

Looking forward to seeing the result!
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chrishet
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« Reply #3 on: May 14, 2012, 09:21:33 AM »
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Thx for the replies...and I appreciate the compliments...I am thinking now that a variable ND filter might be in order - I can snap the widefileld image that I want earlier in the day and then for the eclipse run add the nd filter.  Are Variable ND filters a good buy? or should I stick with say a ND x400 (reduces by 9 stops)?
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chrishet
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« Reply #4 on: May 14, 2012, 09:49:21 AM »
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You may be right about shooting direct using a widefield, and I suspect that is true...I have shot many sunsets without fear.  My concern here is the sun will be considerably brighter as it will be higher in the sky, and I will be taking multiple exposures, perhaps hundreds.  There is an effect known as RBI (residual bulk image) that we see in astrophotography CCD cameras.  This results in a ghost image that appears after imaging a bright star.  Basically is it a residual charge that remains in the CCD for some time, perhaps hours, but eventually fades away.  I can deal with that if it does go away eventually but I am most worried about burning the CCD permanently....I am probably being over cautious, a good ND filter will probably be fine....
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chrishet
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« Reply #5 on: May 14, 2012, 11:33:11 AM »
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I just ordered one of these...

http://www.bhphotovideo.com/c/product/155266-REG/Hoya_A77ND400_77_mm_Neutral_Density.html

I figured it would work well for the upcoming Venus transit as well.
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Wayne Fox
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« Reply #6 on: May 15, 2012, 12:11:30 PM »
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The sun will still be at about 19 degrees above the horizon in California.  A little high for a landscape but certainly possible.  I'm planning on trying to get a landscape type shot of the event somewhere around Cedar City, Cedar Breaks national Monument area to be exact. I'm regretting not taking the time to head to Lubbock Texas and find a cool location of the the event right as the sun sets.

I'm planning on shooting some test shots with various options this week at around 7:30 to see exactly what I think it might take to get the shot I'm working on - I've got 10 stops of Tiffen IR/ND glass, a Singh Ray vari ND and several Lee split ND's.  I think to get any type of landscape shot other than perhaps a silhouette (not a bad option with the right subject) will require split ND's and most likely merging multiple shots.  I also bought a real cheap solar camera filter that I might throw on one camera and focus on getting just a shot of the sun itself with a telephoto.  Optically it's pretty bad, but then I don't expect the sun to be anything but a ring around the moon ... not much detail. 

Landscape photographers take pictures of the sun all the time ... I think the only way you would damage the camera is to use extensive Live View (so those using mirror less cameras might want to be careful) or accidentally over expose the sun by a considerable about.
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chrishet
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« Reply #7 on: May 26, 2012, 11:44:22 AM »
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Here are my results from the eclipse shoot in CA.  I ended up in Chico CA, at The Chico Observatory.  There were about 1000 onlookers there - it was quite an event!

Here are my shots - most of these were taken with a Lunt solar scope.
http://hetlage.com/Gallery/Astrophotography/Solar%20System%20Images/Solar/2012%20Annular%20Eclipse/index.html

Here is a time lapse of the Lunt shots
http://youtu.be/Qa99RbZbreE

and here is one using the Hoya.  I was quite busy with the solar scope and we had Baader solar film filters as well so I didn't have much time to try this filter out, but bottom line is that it worked quite well
http://hetlage.com/Gallery/Astrophotography/Solar%20System%20Images/Solar/2012%20Annular%20Eclipse/slides/Sun_Clouds.jpg

and here is an article I helped write about the event...
http://www.americaspace.org/?p=20033

Thx for the help!



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Wayne Fox
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« Reply #8 on: May 29, 2012, 03:08:58 PM »
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If anyone is interested here's my shot of the eclipse ...



3 shots stacked in PS, manual blend HDR, about 17 stops difference between shot of moon and shot of foreground.

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marcmccalmont
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« Reply #9 on: May 29, 2012, 11:06:06 PM »
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If anyone is interested here's my shot of the eclipse ...



3 shots stacked in PS, manual blend HDR, about 17 stops difference between shot of moon and shot of foreground.



Stunning!
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Marc McCalmont
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« Reply #10 on: May 30, 2012, 11:38:21 AM »
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Stunning!

Agreed.  Beautifully planned and executed.

Makes me wish I'd been there.
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BobDavid
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« Reply #11 on: May 31, 2012, 08:57:44 PM »
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Excellent photograph, Wayne!!
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