pound a tall spike nail (6" at least) into a 1 foot long piece of 2x12 wood. Put an arrow on top of it with a sharpie marker and point the arrow north in your yard using a compass, and over the course of a day mark where the shadow of the nail falls on the board each hour. Then bring it into the woods and set it within view of the camera and point it perfectly north again. Now you have a sun dial that will indicate time fairly accurately as well as be cheaper than a clock. You also know it won't move and set off the camera. [8D]