As for the shutter speed, as long as it is not in the m range, this problem should not occur. You try ISO 100. Aperture takes precedence. I used the original factory, not the vice factory. For asynchronization, synchronization is the most basic requirement. Do you set it as a Hou Lian or a front curtain? Press and hold the flash button on the machine, adjust with the pulsator, and then try again.