I'm loving my flash but am having a few issues. I think sometimes when the flash is maxed out power wise, the photo is under exposed. I see this on the screen and then manually turn up the ISO, then it's fine. Is there a menu adjustment for this? Right now I have my slow limit at 1/60, which I would like to keep because I'm usually shooting my quick moving daughter. Also my x-sync speed is set at 1/160, Is there any reason to have this at anything but the highest setting?