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H-Alpha scope usage at 2017 total solar eclipse

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#1 D.T.

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Posted 13 April 2017 - 12:00 AM

It was suggested to me today that my Lunt H-Alpha solar scope is the wrong instrument for photographing the total solar eclipse.  The reason for this, they told me, was because I will not be able to see the Corona with this instrument.  I was surprised at this statement.  I would be interested in comments on this statement.  Opinion?  Agree?  Disagree?

 



#2 J A VOLK

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Posted 13 April 2017 - 12:31 AM

they are correct - if you want to image the corona you want no filtration during totality. There is quite a difference in brightness between the inner and outer corona, so you would want bracket exposures extensively.

Edited by J A VOLK, 13 April 2017 - 12:32 AM.


#3 SteveInNZ

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Posted 13 April 2017 - 12:36 AM

At totality, it is the wrong instrument. That's when the Moon is blocking the surface of the Sun from view. Totality is the main event, when the sky goes dark and you can see the solar corona with some bright stars and planets. If anything, you want an unfiltered scope or binoculars for that bit.

The H-alpha scope adds a bit of interest to the partial phases for the hour or so leading up to and after totality. You'll be able to see prominences that will become visible to the naked eye at totality but IMHO, that takes away a bit of the magic of totality.

 

Steve.



#4 Traveler

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Posted 13 April 2017 - 02:33 AM

Never understand why some H-alpha Solarscope brands takes a Total Solar Eclipse event as a marketing-opportunity as if a H-alpha scope is the best/only option to see a total solar eclipse...


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#5 MalVeauX

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Posted 13 April 2017 - 04:46 AM

Heya,

 

It's correct.

 

You don't want to use a HA filter, nor a white light filter, during totality. You photograph totality without any filters at all. A lot seem to do this with HDR technique to get the range captured in the small period of time that totality lasts.

 

Of all the points up to totality however, HA or white light is how you do the partial phases of the eclipse. They market for this part of th eclipse and that more and more eyes will be looking towards the sun as that event approaches. Just because they're not used during the shortest phase of the entire eclipse, totality, doesn't mean it's not still interesting to view or photograph the partial phases up to that point.

 

Very best,


Edited by MalVeauX, 13 April 2017 - 04:47 AM.


#6 ESC Velocity

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Posted 13 April 2017 - 08:49 AM

So I was thinking of shooting a series of dslr photos showing the arc of the sun, transitioning to partial then full eclipse and continue the arc after.
I guess you have to start with a filter and then take it off at some point...
But when should one remove the filter? Only at full coverage? 3/4 coverage ? (I would never look through the optical viewfinder without a filter, but I have shot full disk sunsets in live view mode with a telephoto and had no camera damage)

#7 D.T.

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Posted 13 April 2017 - 10:37 AM

Never understand why some H-alpha Solarscope brands takes a Total Solar Eclipse event as a marketing-opportunity as if a H-alpha scope is the best/only option to see a total solar eclipse...

Well, they suckered me in. The marketing worked. I bought my Lunt solar telescope last year mainly because I wanted something to be able to view the total eclipse.  But I didn't buy magic beans.  It's not like I wasted the money.  It's still a great instrument.  Just maybe not for this purpose.  Still the solar telescope would not have been a priority for my astronomy piggy bank.  If I had known it wasn't a fit for the eclipse, I probably would have spent the 2K on a better Astronomy Camera instead.

 

"Never understand"?  Of course you understand.  A sale is a sale.  Companies don't sell to serve the customer.  They sell to make money.


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#8 D.T.

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Posted 13 April 2017 - 10:39 AM

But why isn't the solar corona visible in H-alpha?  The gas is hydrogen.  It's very hot.  It should emit H-Alpha.



#9 Glenn Graham

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Posted 13 April 2017 - 02:07 PM

The corona is extremely hot (1,000,000c). I believe most/all of the hydrogen is completely ionized at those temperatures (the corona's spectrum includes iron ionized 13 times) so wouldn't be emitting in H-alpha.



#10 Glenn Graham

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Posted 13 April 2017 - 03:56 PM

Just a follow up... This is why the corona does not take on the pink color you see in the chromosphere during a total eclipse (lower temperature prominences emitting H-alpha+H-beta).

 

When I was a high school student, I was a volunteer for our local planetarium during the '79 eclipse. The members of the staff were amazing mentors for us young astronomy "groupies" producing shows and teaching at our local summer camp. One member was eager about the opportunity to view the "flash spectrum" during the eclipse and was extremely moved by it when he saw it. At the time I was wrapped up in observing and photographing the corona and didn't realize how special the flash spectrum was in the history of solar physics. While the solar spectrum most of us are familiar with is a continuum with absorption bands resulting from elements in the sun's atmosphere (and our own), when the sun goes into full eclipse the absorption spectrum will be replaced by an emission spectrum of the elements in the chromosphere. When first observed, there were a number of lines that didn't match any known element... including a yellow one named for the sun (helios)... helium! Terrestrial He was identified 27 years later.

 

In honor of Gary I will be taking a pair of "rainbow" glasses to see if I can catch the flash spectrum for a few seconds as totality ends.




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