What's wrong with the camera and the lamp?

1: See if the output on the lamp is too small. If the aperture of F 10 is too small, you can't see anything.

2. There may be something wrong with the synchronizer. I have encountered this problem before, so I can try something else. (Wireless is prone to this problem. )

3. It takes a little time for the studio lights to come back, and then shoot after there is a buzzer. If the output energy of early shooting is insufficient, there will also be a black screen.

The only certainty is that the theoretical synchronization speed of D40 is 1/500S, which is a hybrid shutter with mechanical and electrical coupling, and can achieve complete synchronization. I tested it on D70, so it has nothing to do with speed.