Even if you've been living under a rock, you've probably heard there is a total solar eclipse crossing the United States on Aug. 21. Total solar eclipses are very rare — once in a lifetime — and cross the US even less frequently. This is an event not to be missed.

Because of their rarity, planning to see or photograph the solar eclipse can be a little theoretical. Here are my plans at a high level. For more details (including rationale and discussion), check out my much longer and more in depth blog post here.

Location, Location, Location

The first thing you need to know is that the entire country will see at least a partial eclipse. But that isn't the really spectacular part. You want to be in the narrow 100 kilometer wide path of totality which will travel across the country from west to east. In fact, you want to be as dead center on the path of totality as possible.

Luckily, in 2017, finding a viewing locations is pretty simple and there are literally thousands of miles of totality to pick from. This interactive google map of the eclipses path shows you exactly where you can be, and also the contact times (more on that in a second). The path of totality is outlined in red with a blue line down the center. And for a text based description of where to be, check out eclipse2017.org's rundown of locations by state.

What to Expect

There are three types of Solar eclipses — partial, annular and total. Partial eclipses occur when the moon passes over the sun glancing along one edge. Annular solar eclipses occur when the moon passes directly over the sun, but because the moon is at a far point in its orbit, is too small to cover the entire photosphere.

A total eclipse is something much more special than either of those. When the moon is at its nearest during new moon (what would be called a supermoon at full moon) and the sun, earth and moon align, the moon will fully cover the photosphere of the sun. It will get dark during the day time and you will be able to see the stars and even the whispy corona of the sun.

Using the interactive map linked above click on the location you plan to be at and a bubble pops up. There is a lot of information here, but there is two key pieces:

• C2 – This is the time (in UTC) when the moon will first fully cover the sun. C2 is the start of totality.
• C3 – This is the time (in UTC) when the moon will stop fully covering the sun. C3 is the end of totality.

Depending on your location C2 to C3 will be between 1.5 minutes and 2.5 minutes. And the time from C2 to C3 is THE MAIN SHOW.

Check out Smarter Every Day’s video about what to expect for more details, or see my longer blog post for more in depth discussion.

Photographing the Eclipse

The sun is bright. Just about any modern digital camera can photograph the eclipse. You need some safety equipment (see the Safety section) to protect the camera and your eyes and a long telephoto or super telephoto lens. A tripod is also advised, and you probably want an intervalometer so you can let the camera click away on its own while you watch in awe.

Lens Choice

When selecting the lens you plan to use, there are a couple of factors to remember:

• The sun and moon are both about half a degree wide in the sky.
• You can determine how big the sun will be in your frame by looking at the horizontal field of view for the lens you choose on the camera you use.
• The sun is a moving target. It moves ¼ degree per minute. If you plan to shoot without moving the camera, your field of view needs to be wide enough to capture the entire movement from just before totality to just after, or about 3 degrees.

As an example, I'll be shooting with a 200 to 500mm at 500mm on a full frame camera. It has a field of view of about 4.1 degrees horizontal. The sun will be about 12% of the width of the frame.

For a more in depth discussion of focus lengths, movement and lens choice, see my full blog post.

Camera Settings

I plan to have my cameras in manual mode for the eclipse.

Prior to C2 (totality beginning) you are basically photographing the naked sun. The portion that is partially covered by the moon will not affect exposure much at all. That means it is easy to test (with the right safety gear) any normal day.

In my case, the settings I use for regular sun pictures are equivalent to ISO200, f/8, 1/1000s WITH solar film. My solar film blocks about 16 stops of light, but you should test your film when you get it because it might be different.

When totality starts (at C2) things will change dramatically. The corona, which will be all we can see of the sun, is about 20 stops dimmer than the photosphere. Removing the solar film just before C2 will compensate for 16 of those 20 stops. Depending on your camera and settings, it may be ok to leave it or you might need to boost the exposure though shutter speed, ISO or aperture.

Focus

With solar film installed, it is relatively easy to autofocus on the sun. And, the sun doesn’t change distance to the earth on a minute by minute timescale. Focus your camera and then switch to manual mode. Don’t bump the focus ring!

Safety

The sun is bright (we already covered that) and you can set things on fire with a low quality magnifying glass… Pointing a high performance, bright telephoto or camera lens at the sun can be dangerous to your eyes and your camera’s sensor and electronics.

RULE ONE: NEVER look directly at the sun with your naked eyes or through an unprotected telescope or lens. Sun glasses are NOT adequate protection. The best protection are custom designed solar viewing glasses such as these: http://amzn.to/2t19O44

The only exception to Rule One is during totality when it is safe to remove your solar viewing glasses.

RULE TWO: Never point an unprotected camera at the sun. The lens is gathering and focusing a huge amount of energy. Especially on mirrorless cameras, that energy is being dumped directly into the sensor and electronics of the camera. Use solar film or a solar filter to shield the camera from most of the energy. Here is the solar film I use: http://amzn.to/2sN5PEh

As with Rule One, you can (and should) remove the solar film during totality when the moon is blocking most of the sun’s energy.

To see how I use the solar film, check my full article here.

Conclusion

The 2017 US eclipse promises to be one of the most photographed astronomical events in history. Millions of people are going to see it. You should be one of them. Even if you don’t photograph the eclipse, go see it. It is a once in a lifetime event.