So I'm trying to take a self-portrait and I can't get the focus quite right. I'm using the timer and since I'm not in the shot when I set it up I'm just guessing on the focus. Any ideas? So far I've thought of focusing on the backdrop and then reducing the focal plane manually by a foot or two or I thought maybe I could put something up about where I want to stand. Anyone tried this before? How'd you do it? Camera is a D70 with 18-70mm Nikkor.