The Eclipse by the Numbers

As I continue my plans to see and photograph the April 8 solar eclipse, I felt like it might be useful to share of few numbers I discovered when I photographed the August 2017 Great American Eclipse.

I used Adobe Photoshop to create this illustration to help viewers picture what is happening during a solar eclipse, showing what it would look like if you could see both the moon and the sun's corona. The image of the moon is from a lunar eclipse in September 2015, and the stellar corona is from the August 2017 Great American Eclipse.
I used Adobe Photoshop to create this illustration to help viewers picture what is happening during a solar eclipse, showing what it would look like if you could see both the moon and the sun’s corona. The image of the moon is from a lunar eclipse in September 2015, and the stellar corona is from the August 2017 Great American Eclipse.

But first, a note about attitude: the coming eclipse has the potential to be a truly amazing experience, but it also might turn into a disappointment or even a fiasco for many trying to see it.

  1. It is entirely possible that there could be cloud cover where you are.
  2. It is also possible that traffic will be heavy, and you might not get where you want to be. Therefore…
  3. Try not to take any of it too seriously. Viewing and photographing a solar eclipse is a ton of fun, but it’s definitely not worth getting into conflicts with other eclipse viewers, authorities, or even family and friends.
  4. Remember that this eclipse traverses a huge swath of Mexico, the United States, and Canada, so there will be literally millions of people seeing, trying to see it, and photographing it. So…
  5. Set aside any notion that what you are doing is important. If it’s not fun and lighthearted, it’s not worth doing.
  6. Don’t speed or drive recklessly. Stay off your phone. Leave early and be patient. Crowds and traffic can make driving more dangerous, and can delay the time for help to arrive if something goes wrong.
  7. And if you get stuck in traffic or it’s cloudy, have a “pact of acceptance” (as my sister and I will), such that you can smile, relax, and have fun anyway.

So, some numbers. When I photographed the August 2017 event, I hadn’t photographed an eclipse before, so I was deciding on settings as the event happened.

Retired East Central University Physicist Dr. Carl Rutledge discusses the mechanics of solar eclipses Friday, Sept. 22, 2023 at a meeting of Ada Sunrise Rotary at the Aldridge Hotel.
Retired East Central University Physicist Dr. Carl Rutledge discusses the mechanics of solar eclipses Friday, Sept. 22, 2023 at a meeting of Ada Sunrise Rotary at the Aldridge Hotel.

I used my 400mm f/3.5 Nikkor lens with a 1.4x teleconverter on it, creating an effective 560mm f/5 lens, on a sturdy tripod. I’ll probably be using this same setup again.

My first exposures of the totality were a guess at f/8 at 1/160th at ISO 200, and was a little too dark to capture much of the corona, the white, feathery part of the sun you can only see during an eclipse (or with an expensive astronomical device called a coronagraph). For my main photos of this phenomenon, I shot at f/8, 1/80th, ISO 640.

I used f/8 because many lenses are sharper if you “stop down” (use a smaller aperture) a value or two, and I know this lens/converter combo would be sharp at f/8.

My most recent eclipse experience occurred last October.

This is a frame just as totality occurred during the October 2023 annular solar eclipse. During such events, the moon doesn't completely block the sun because the moon's orbit isn't a perfect circle, so it is slightly farther away than during a total eclipse.
This is a frame just as totality occurred during the October 2023 annular solar eclipse. During such events, the moon doesn’t completely block the sun because the moon’s orbit isn’t a perfect circle, so it is slightly farther away than during a total eclipse.

On my drive back home from a trip to Las Vegas, I drove north from Gallup, New Mexico, knowing it would take me into the path of the annular solar eclipse. As I drove north, I saw more and more people on the side of the road, at wide spots, in turnouts and parking lots. I picked one group at random, and everyone was glad to see me. A nice lady from Oregon is gave me a homemade “celebratory cookie” when it was over.

So have fun, be safe, and have a cookie.

1 Comment

  1. Assuming we don’t eat them all while we’re in the road, our celebratory cookies will be “almond joy”. Yum.

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