I'm shooting a wedding this month and I found out it will be outdoors at about 3:00 pm. Further I found out this week the bride wants the "formal" shots to be done at the same location this Sunday. My question is: I have read that for "fill" flash outdoors you meter as if the flash was not present and then lower the aperture by one stop. But is this for when the flash is either on top of or close to the camera? I detest the look of frontal, on or very near camera flash and had planned to take along a stand and umbrella and position them as a true fill light to the ambient sunlight. But so far I have not figured out how I would determine a correct exposure. I'm probably missing something very simple here. Can someone "splain" it to me? I will be using a Mamiya 645 for the shoot and it syncs at a 60th. I will be using Portra 160 film. The flash I will take is a Sunpak 611. I have a Gossen Luna star F meter that will meter incident,reflected and flash as soon as I can figure out what to do.