I have a question about flash settings. For the Nikon SB 700 in Slow Sync + Rear Curtain mode the flash fires twice, at the beginning and then again at the end of the exposure. Is the first flash only for metering and the second flash is the one that appears in the picture or is it like 2 flashes in the same exposure, one at the beginning and one at the end? Thanks for the help! Marlton Mom PS. this flash arrives tomorrow so I don't have the manual quite yet.