I have had very good results using http://www.scribd.com/doc/2604955/jiffy and only shooting one exposure with slide film. If you can nail the exposure with one exposure on slide film, you can't get much better than that. In fact for night photography, I use this rather than my in camera light meters [Nikon SLR] or Hasselblad, or even my Gossen. Light meters end up over compensating for the unlit areas, unless one uses a spot meter.