I have the Geotagger Pro 2 which I received a couple of days ago. When set to auto, it works as the manual describes when used on my D300s. That is, the unit powers on and off with the camera. I will have to check but i think this only occurs when the Geotagger is mounted on the hotshoe. I don't have the Geotagger with me right now so i cant confirm that. Also, I have not yet put it on my D800 but I will give that a try. It might be a day or two before I have them in the same place. You indicate you have both a D800 and an E. Does it do the same thing on both?