As someone suggested, I purchased a Yongnuo RF603C II, for use with my Canon 7D and realize now, that I don't understand flash lighting. As a test, I was photographing a chair in indoor daylight & used a fairly fast exposure. At 1/320s, F32, ISP 100, the picture is over exposed. When I reduce the TV, to 1/500x, keeping the F-stop and the ISO the same, the top half of the picture is correctly exposed, but the bottom half is black. I haven't found a solution online and would appreciate any suggestion you may have.