A Sunpak 611. Lets you use every drop of available light first. The near-worthless power rotary-switch is easily modified by a hand-crafted end of a 120 reel, some sandpaper for roughening, and some thick crazy glue. Remember to make a printed copy of that dial, because you're about to glue it covered-up. Glue the printed copy to the new face of the rotary-switch which in now the interior side of the 120 reel, sawed-off. From that point on, do everything in manual mode, meter everything with your luna-pro, and turn that flash up enough to keep away from the toe of the film curve. It's a powerful flash--you can make available light the fill light a lot of times. Sunpak 611--remember that. Or get a Honeywell and make a bunch of ND attachments. I like the Sunpak.