Thanks for the compliments. Like most pictures, being in the right place at the right time...
Phil, I have a now aging Nikon D800 with a Nikkor 28-300 lens. On tripod, set to 28 mm, manual focus, with setting the lens to the mark on the distance where I have determined in daylight where infinity focus is (unfortunately the focus ring goes a little bit beyond, so just setting it all the way to infinity doesn't give perfect distance focus. I set the camera to Program mode, wide open f/stop, and 16 seconds on the time. I opened the shutter, and when the time was up, opened it again for about 300 or so shots.
I was fortunate to have almost continuous lightning although perhaps 1/2 to 3/4 of the shots were not 'interesting', but it wasn't film, only digital images so I didn't feel I wasted anything.
My camera does have an intervalometer function so rather than have to push the shutter release all the time, I could have set that up, but I hadn't prepared, nor had I taken any readings before going out to determine a good interval to expose for, which is where the 16 seconds came from with early shots against the twilight sky, and I just didn't change them since the lightning provided about the same light as needed.
Far too often there are preceding showers and the view of the storms is obscured by rain or intervening clouds. These isolated storms were a rare treat here (unlike the desert southwest where that is more of the norm, I understand). That, along with the near full moon for extra light to highlight the clouds helped. Hope this helps with getting you out there taking the photos when your conditions present. Dale