I just got an old flash from my grandpas old camera. I just picked up a softbox lll. When I shoot in manual, I only get half a shot. The only part of the photo that comes in is the top half while the bottom half remains dark. When I shoot in any other mode the whole picture is just overexposed. I'm using a t1i, vivitar 2800, 150mm sigma, and a softbox lll.