Visit his site for more info and photographs. For best results, use 100 speed slide film for lightning, such as FujiChrome Sensia 100. All types of film will work, but slide film yields the finest detail and the highest picture quality. For years I used standard 100 speed print film because of its low cost, but recently switched to slide film for its remarkable quality. Lightning bolts appear clearer, crisper, brighter and more detailed on a slide.
Slides also tend to pick up more cloud detail and show deeper and more appealing colors.
I used to employ 100 speed print film because it's the most economical. Again, slide film is expensive- one 24 exposure roll of 25 speed film costs as much as four rolls of 100. The slower the film speed, the longer you can leave your shutter open. Faster film speeds will work, but the picture quality may not be as high. Have extra film ready.