It is hard to count the number of times I have been asked the question, "which camera is best for photographing the eclipse?". The simple answer is almost too simple for most to accept - the best camera is the one you know how to use best. Everyone expects an endorsement of a particular brand or type of camera system. Here is the thing, you can get a great picture with any camera. You just need to realize what it can do and how to do it.
The best thing is to start now! Months before the total solar eclipse you need to begin mastering your camera and lens setup. Practice! The practice subject is the Moon. Take a variety of exposures to see different details but more important to the solar eclipse imaging - to learn how to adjust the camera in the dark. During totality it will be kind of dark and you might have trouble reading the camera settings. You want to train yourself to where you can almost run the system with your eyes closed.
During the eclipse is not the time to learn how your camera works. You should be an expert at your own camera. Trying to jam in a bunch of tips and tricks from the experts at the last minute will result in frustration most of the time. If you just bought the camera and have not used it much, don't try to use it during totality.
The August 2017 TSE will last under three minutes at the longest points of duration. It will be more like two minutes for most observers. And it will seem like 15 seconds. Spending that precious time playing with a camera is not worth it. The experience alone is worth it.
Tip: Take pictures of the cool telescopes and long lenses with their owner/operators. Then trade email addresses to send them a copy in trade for one of their eclipse shots. This way you can get a great variety to show off to those that chose not to go to the eclipse.