I usually just take a series of 30s shots and toss out the ones that don;t have lightning in them.
To help do this during twilight I have a few ND filters I put on the lens (also useful for smooth water shots
) but I don;t have enough to get 30s in full daylight.
As for the lightning triggers, the theory is that the lightning strike is actually 4 to 6 short strikes over the same track spread out over many milliseconds. The first strike is detected by the trigger, and the shutter is opened before the last strike.
Al.