Panny, you sure do like a challenge. Why photograph an item at night that is 100 meters distant? Could you not get closer? At that distance you would not need a flash, you would need an airborn flare or similar source of illumination like sunlight. I'm beginning to think that your thread may be a ruse.
Sony A57 with 18-55 kit lens, Sony A200 and Sony H70
50mm f3.5 Minolta Maxxum macro
24mm f2.8 Minolta Maxxum
100-300mm Minolta Maxxum APO Zoom
70-300 Sony apo G SSM Zoom