I thought photographing birds in flight was difficult, until I tried going after dragonflies! I was pleased with this one, though.

Top to bottom: A male rather ragged Emperor Dragonfly defending his patch; a Brown Darter; and a second, fresher looking Emperor a little upstream. Worth zooming is a bit to see the detail.

My wife was very patient waiting for me to get my shots, and helped explain what I was doing to passers-by on the canal who saw me pointing the camera at random, apparently empty spaces!