We tested this the other day. Theory is bad. You are shaking as you pull the string tight. In most cases even more so than when you are at rest just holding the Camera. We tested with a Canon 20D and lenses from 10mm to 300mm. We shot a 15 x 15 CM grid, at speeds down to 1/8 sec. Base image used tripod. Results showed in camera/lens stability best. Hand holding second, 1$ Stabilizer third. I really wish this method worked better, but at least for the three of us who tested it, we are sticking with hand held.

I don't think this is a new idea. I've heard many photographers give this tip before. But given TC's results, I guess YMMV.

Great Idea, thanks