Flash sync speed in AV mode in EOS 1Ds Mk2?

the camera has no idea what it's seeing. so, it will use a long exposure to gather what it thinks is enough ambient light. in this situation dial the exposure down to reduce the amount of ambient.(speedliter's handbook syl arena) or set the 1 DS II on M / ISO 200 / f5.6 / 1/250 and the 430EX also on M / ISO 100 / f5.6 the only thing you have to do is to change the ISO valua