I am delving into the world of strobe photography and have been having a difficult time controlling the light output of a 600W off-camera strobe using the sync cable. It doesn't seem like the output power dial makes any difference in the exposure. Here's what I'm using: GH3 with a Mettle 600AD strobe -using the sync cable to control the shots for now. Will get a wireless trigger if the need arises but with mostly studio shots to do, I'm not expecting to that soon. It looks like it shoots full-power no matter what I adjust. I have to stop down the aperture well into the f20 range to control the exposure and that affects the sharpness of the image due to diffusion. I can't increase the shutter speed faster than 1/250 or I get black bars over the image. The menu options don't look like they help either -meaning I can't seem to adjust anything regarding power or timing in the camera that makes any difference to the strobe through the cable. Would a wireless trigger help here? My fear is that I either have a broken strobe that just ignores the power output dial, or there's no way to control the output through a sync cable... Can anyone help here?