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As the fateful day draws closer, the United States will host a celestial event that comes once in three generations. I plan to witness this first hand at the exact center of greatest eclipse.

In the planning of this, I have immersed myself in the work of Eddington back in 1919, confirming Einstein’s General Theory of Relativity (and its explanations for gravity) was right.

I personally, could not just stand-by and just look at this event and not do something more. Knowing that failure, due to weather, equipment, and or other forces are stacked against me, I have to make an attempt because a chance like this will never present itself again in my lifetime.

My goal in coming here today is simple, I need some advice from someone who knows telescopes and cameras.

The equipment I plan on using is :

  • a 150 mm Celestron 6SE with an automatic GOTO mount, and an equatorial wedge.
  • The camera will be a Sony A 6000, with an adapter.

TThe field of view is large because of the 1500 mm focal of the telescope. I chose device because of a trade-off that has to be made, Eddington used a 100 mm refractor scope when conducting his experiment. With any shift in the apparent position of the stars behind the sun as Einstein predicted, the 150 mm telescope should, in theory, coupled with a camera that has a 24-megapixel sensor, have the necessary resolution to image this shift like Eddington's image. If any shift to the stars is to be captured, they will appear within close proximity surrounding the eclipse.

My problem is as follows, the telescope I will be using, will be the lens, and now the lens has only one f-stop. At f/10 and only having the ISO and shutter speed to work with, what exposure would I use ?

Knowing that a long exposure would only manage to capture the outer corona, and possibly engulfing and obscuring any stars that shift. Likewise, a shorter exposure would capture the inner corona and thus not image any stars at all.

I do however plan to bracket 5 stops (shutter speeds) to better my odd of catching any shift.

Would anyone have any other useful tips trick to further better my odds in my endeavor?

Thanks In advance

Bob Brooks

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    $\begingroup$ You might also consult with the Astrophotography forum at dpreview.com. Can't hurt. $\endgroup$ – StephenG Jun 8 '17 at 23:28
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    $\begingroup$ This should be migrated to photo.SE , where the general topic of solar observation is discussed. $\endgroup$ – Carl Witthoft Jun 9 '17 at 12:55
  • $\begingroup$ it's not clear whether you have any/much experience in astronomical photography, but from what you have said, I infer not very much. If that's the case, then worrying about exposure times may be not your biggest problem. The gravitational deflection is tiny, so you will need to have the telescope very accurately set up, since the exposure time will introduce errors greater than the the deflection you are trying to measure. $\endgroup$ – Dr Chuck Jun 9 '17 at 23:43
  • $\begingroup$ @Dr Chuck, your assumption is correct, I have no experience with astrophotography. I did however, made a reasonable conclusion that any advice worth following, might come from this forum, I know now I was wrong. $\endgroup$ – Bob Brooks Jun 11 '17 at 0:14
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    $\begingroup$ While I applaud your desire to repeat Eddington's measurements, I strongly urge you to re-consider. You only have a few minutes of totality, don't waste them futzing around with a telescope & camera! By all means, set up the `scope and camera and let them do their thing on automatic, but please devote your personal attention to the most spectacular astronomical phenomenon that one can witness without leaving the planet. $\endgroup$ – PM 2Ring Jun 12 '17 at 2:38

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