Hi S,
I think the max sync speed on your 200 is 250th if you are shooting hard wired to the flash head. Thing is S, its the duration of the Flash that freezes the image and not the speed of the shutter so don't worry about shooting at about 125th, it will be just as sharp as any othe setting you may use. Try 125th and you should be fine, if you are getting a little ambient light creeping in at this setting just increase your apreture. If you don't want any ambient light at all in your flash shots try shooting with the flash switched off and if the images are black (no light) at 125th of a second your done, just switch the flash on and adjust the power of the flash to your requirement.
If you can still see an image when the flash is switched off then adjust you apreture to a higher number e.g. from F5.6 to F11 then try looking at that test shot.
Remember to switch your flash back on after looking at the black out test shots.
Hope this helps?
Good luck,
Anthony.....
