[QUOTE]\nIn message <iRMOe.8479$Us5.3882@fed1read02>,\n\n\nThere's no comparison. High-speed flash sync is a totally different\nthing than normal sync-flash. With the 550EX, the flash intensity at\n1/200 would be 4x as strong and down to about 1/12 the duration of the\nhigh-speed-sync at 1/250. High-speed sync flash is like a strobing\nambient light during the period of exposure.\n\nI learned the hard way that enabling high-speed-sync and going 1/3\nfaster on the shutter speed can mean a loss of sharpness with telephoto\nand flash. Think of it as supplementary light; not flash.[/QUOTE]\n\nThat's a better way to word it, and I frankly am not completely clear on how \nit works out.\nYou're right that it quickly becomes unable to provide a main light.\nI was afraid that some people might have assumed the poster meant you \nsomehow couldn't use flash above 1/200th, which of course isn't true.\n\nI like the way you explained it.