Photographing lightning is similar to shooting fireworks. Both require an open shutter which is a long exposure, but the trick is shooting at a large aperature or f/stop (smaller number like f/4).
© David Sanders
If you shoot at f/16, the lightning looks like thread on your photo and not very dramatic. This is a single burst of lighting (one bolt that flashed for brief second) and captured at f/5.0 at a 30 second exposure at ISO 100. I didn′t use a lightning trigger or similar device, just a long exposure, big aperture, and a little bit of luck.