Hello. Just found this fourm, and am going through the old posts and came across this post. I have a "overall" simple formula that has worked for me. You HAVE TO have a camera where you can adjust the ISO and apeture. I.E. Digital SLR.
Here is a "basic" formula to follow... (For digital camera users)
If the lighting is 2 or more miles away, (10 or more seconds after flash you will hear thunder) you will want to use ISO 400 speed, and around f/4.0. Set your camera on a tripod, and compose your shot in the direction the lightning is. If there are existing lights, (yard lights, houses) try a 30 second exposure, and see if the lights are blown out, too dim, or look properly exposed. Adjust aperture to get a properly exposed 30 second picture. If you have to stray too far from 4.0, then you may need to move farther away from the lights. Once you have a properly exposed, 30 second picture, you are set. As lightning strikes, it will just add to the picture. So you now have the properly exposed foreground, with lightning bolts in the frame as well. Kinda like this...
Now... as the lightning gets closer, bring the ISO down to 200 or 100 depending on how close it is. Also close the aperture down to f/8 or so. Again, make sure the existing lights are properly exposed, and the lightning will look just fine. There is no exact way of doing it, as lightning can be brighter at times. Lots of variables such as how much moister is in the air, is the lightning in rain or not etc. Best advice is to look at each picture that has lightning and adjust it until you get the right looking picture.
If the lightning is really close, you may have to bring the ap down to f/16 as in this shot...
And that was still not enough to keep one of the bolts from washing out.
The 30 second thing only applies if 1 to 3 bolts are occurring in that 30 seconds. If it is more frequent, you may need to bring the time down. Hope this was a help to you. If you have any more questions, please ask.
BTW if the lightning gets this close...
Pack it up and go home. Its not worth it.
Here are all of my lightning pics...
http://www.wxnut.net/lightning.htm
Doug Raflik