Lightning

As you can see, the foreground exposure is o.k. but the clouds are overexposed. I wanted a darker sky since this is a night shot --4 seconds at f8. Is this because I should have used a 100 ISO film rather than NPH@ 320. Please advise and crtique. Thanks.

The grass in my opinion adds a lot--musta been pretty windy? Its a really cool effect. Haven't really had much experience shooting lightning, however I did come upon an article about doing it just yesterday so I thought I'd pass that along:
http://photography.about.com/library.../aa072103a.htm