2017-07-29T17:34:41Z

Preparing For The Great American Solar Eclipse

Posted by Miguel Grinberg under Photography.

If you live anywhere in North America, write down August 21st, 2017 in your calendar. This is the date of the next solar eclipse, one that is of particular interest to us living in this continent, as everybody will be able to experience it in some capacity regardless of location. The map below, from NASA, shows the swath of the United States in which the eclipse will be total, and what percentage of totality you will see anywhere else (click to see a larger version).

In this short article, I want to give you some ideas on how to prepare to view and photograph the eclipse in a way that is safe for you and your camera.

What is a Solar Eclipse?

You probably know this, but just in case, an eclipse occurs when the moon happens to pass in between the Earth and the Sun. When the three bodies are in a direct line, the moon casts a shadow on the Earth's surface. Watching the eclipse from Earth, the sun is obscured by the black silhouette of the moon. If the alignment is perfect, you have a total solar eclipse, which causes the Earth to go mostly dark while the sun looks like a thin ring of light:

Solar Eclipse

While total solar eclipses happen fairly often, the chances of one being visible from your location are quite rare. According to this analysis, a total solar eclipse is visible from a given location once every four or five centuries, so this might be the only chance in your life to see one!

Best Spots to View the Eclipse

The map at the top of this article shows a band that runs through the continental United States from North West to South East. That is the path of totality. All the places covered by that band will see a total solar eclipse. As you move away from this band, the more the moon will "miss" the sun and cover it only partially. If you want to know how the eclipse will look from your location, find yourself up in this nice interactive map. If you live anywhere in the US, Canada or Mexico, the eclipse will be visible to you!

I am located in Portland, Oregon, which is not in the totality path, but very close. I need to drive about 30 miles South to get to an area from where the eclipse will be total. Assuming the highways that day are not completely blocked by thousands (millions?) of people trying to get to the totality band, I plan to make the trip and experience my first and possibly only eclipse in the best possible way.

How to View the Eclipse Safely

I'm sure you know that looking directly at the sun is bad for your eyes. If you are in a region that is outside of the totality path, the sun will never be fully covered by the moon, so you cannot look at the eclipse directly at any time. If you are in the totality band, you can only look at the sun with the naked eye during the minute or so that the eclipse is total, which means that the sun is fully covered by the moon. If you are thinking you'll use sunglasses, forget it, those are not strong enough to protect your eyes against the sun.

So how you do view the eclipse if you cannot look at it? There are special glasses that you can use that have strong filters that will protect your eyes during all the partial stages, before and after the eclipse gets to the total phase. These don't need to be very sophisticated, you can buy cheap cardboard glasses on Amazon, for example.

Eclipse Glasses

How to Photograph the Eclipse Safely

Now, if you also want to take photographs of the sun during the eclipse, you have more shopping to do. Taking pictures of the sun is dangerous for your eyes if you are trying to compose your picture by looking through the camera's optical viewfinder, and also potentially bad for your camera, which can get its sensor burned if it is pointed directly at the sun excessively. Using standard neutral-density filters is not enough unfortunately, you would need a lot of them stacked to filter enough light to not make direct sunlight into your camera dangerous.

A best option is a filter for your camera similar to what is used in the solar viewing glasses. A month or so ago when I was shopping for a filter on Amazon, there were several that were made for telescopes, but that could also be attached to a DSLR lens. Looking again today I see that all of those are out of stock. The best I could find are these solar filter sheets that you can use to build your own filter. The solar filter that I purchased for my DSLR attaches to the front of the lens with three screws, and looks like this:

Eclipse Glasses

If you can find one of these, I think it is a good buy. Else you'll need to figure out how to build your own filter using filter sheets.

Assuming you find a filter to protect your camera sensor, the next thing you are going to need is a camera with a good optical zoom or telephoto lens. Why? Because if you take a picture of the sun with a normal lens, the sun is going to be a tiny spot in your picture. To take a good clear picture of the sun you need as much magnification as you can find. I shoot with a Canon DSLR, and will probably be using a 400mm telephoto lens to photograph the eclipse. This lens is not the best, but it's the longest one I have (I haven't decided if I want to invest in a longer and better lens for this occasion yet). Below you can see a picture I took of the sun at midday, using this lens and the above screw-on filter. This is a straight picture from the camera that I have only cropped, since even with a 400mm lens, the sun occupied a fairly small portion of the frame.

Sun

If you want to see how much of the frame I had to crop with the 400mm lens, here is a scaled down version of the complete frame:

Sun

If you want to have an idea of how pictures of the sun will look with your lens, this page has many sun photographs taken with a different focal lengths.

How to Get the Right Exposure

So let's say you have the filter and the telephoto or zoom lens. How do you get great pictures of the sun during the eclipse?

The camera must have a fully manual mode, because this is going to be a quite difficult image for the camera to figure out the exposure on its own. I focused it on infinity, and then arrived at the correct exposure by experimentation. I recommend that you practice before the eclipse by taking pictures of the full sun. i should note that even with the solar filter on, I did not want to risk my eyes by looking through the camera viewfinder, so I've used the "live view" feature of my DSLR to look at the exposure on the LCD screen.

I randomly started from ISO 100, f/8 and found that I could get a good exposure with 1/500s shutter speed, which was great, because at that speed I could take pictures handheld. The resulting picture with these initial settings wasn't very sharp though, so I then shot a lot more tests varying the settings. The picture you see above was shot at ISO 800, f/22, 1/500s. From all the test pictures that I took, I found that for this specific lens (which is a fairly cheap, off-brand zoom lens), shooting at f/22 gave me the sharpest result. For that reason I had to compensate the exposure by increasing the ISO to 800.

Have Fun and Be Safe!

Please remember that you should never look directly at the sun! If you have kids with whom you will share this experience, make sure they know they need to keep their glasses on at all times.

What are your plans for eclipse day? Let me know below in the comments!

3 comments

  • #1 Jackie said 2017-08-01T09:09:43Z

    good, but I'm in china, would got that chance.

  • #2 Miguel Grinberg said 2017-08-01T16:25:01Z

    @Jackie: Looks like there is a solar eclipse in 2035 that is going to be visible from Beijing. You need a bit of patience! See https://en.wikipedia.org/wiki/Solar_eclipse_of_September_2,_2035.

  • #3 Kyle Lawlor said 2017-08-04T00:49:05Z

    Did not have anything planned! I didn't know that it would be partially visible at my location. But now I will definitely be making plans :D

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