Canon Explorer of Light Ken Sklute has put together an article about shooting the recent total solar eclipse for the Canon Digital Learning Center.
From Ken Sklute:
I finished setting up my arsenal of Canon goodies for the morning. I was using the Canon EOS-1D X Mark II along with the EF 200-400mm f/4L IS Extender 1.4x lens atop my ReallyRightStuff tripod. I chose the 200-400 just in case we were visited by overcast skies. If those pesky clouds did come to visit, I could zoom out to potentially make use of the clouds in my composition. We were lucky as only a few high cirrus clouds came by for about 30 minutes during the partial phases. They soon moved on, as the star of the show got ready to make an appearance.
I also had an AZ-EQ5 German Equatorial/Alt-Azimuth mount from Sky-Watcher, keeping my two EOS 5D Mark IVs tracking the sun as it moved, one with an EF 600mm f/4L IS lens and the other with the EF 400mm f/5.6L with a 1.4 converter on it, giving me a focal length of 560mm. I was firing the two 5D Mark IVs simultaneously from a hub that allows one cable release to fire multiple cameras. Read the full article
The next total eclipse is on July 2, 2019 and will be seen by a small part of South America, and the next total eclipse in North America will occur on April 8, 2024.