Freezing a hummer in flight

This is a green crowned brilliant hummingbird I photographed in Costa Rica. I used three flashes -- one for the background, which was a 20x30 inch matte print of out of focus foliage, and two for the bird placed on either side of it. I had to use the print because otherwise the background would be black. Since hummingbirds are not nocturnal, a black background would not appear to be biologically correct. I turned the power down on the flashes to 16,000th power. That, in turn, made the exposure time about 16,000th of a second. That's why the wings, which are beating about 80 times per second, are tack sharp. I varied the exposure by adjusting the flash-subject distance. The lens aperture was f/6.3, and the ISO was 400.