Hi everyone. I had just acquired a demo ND in very good condition. But the battery seemed to be sucked of its life everytime the camera is left alone for a couple of days. I have not been able to shoot beyond 30 images in JPEG1. Is there something wrong with the set or is this the usual life-span of the batteries. Does it mean that I have to remove the battery when not using the camera even only for a few hours? Thanks for helping.