I'm just beginning to experiment with "light writing" but I'm not sure how to get the effect I'm looking for. I saw an article in "Practical Photography" magazine where the subject was writing a word with a sparkler. They used an off camera flash midway through the exposure to capture the person doing the writing. I tried this, but my subject is still blurred. Can somebody please tell me what to try to get the person doing the writing to be in focus and not just a motion blur?