Okay, I do a lot of low light shots using a speedlight 430ex with a Canon 350D I find that 800 or 1600 ISO handheld with the flash still results in blurred pics. I happened to shoot a few at 100 iso with the flash, and they freezed the motion perfectly (though the background was darker of course). Any tips? What is the ideal ISO for lowlight with a flash? Should I stick with a lower ISO?