I've recently tried to use studio lights with a DSLR Nikon D70. Setting the camera to 60th at f11 and using a hand held metre to adjust the studio light to that strength.I took the shot the lights seem to go off but all I get is black way underexposed. I'm using a slave set up with the on camera flash pointed to the ceiling. ISO is set to 200 on camera and on the light metre. Could any suggest what may be the problem. I've had no problem using a film SLR with these lights.