Garry, Many thanks. I am completely filling the grey card so your comment about calibration of the camera may be right. Before I went outdoors to do the test properly I tried it indoors in natural but rather poor light for practice, and to get a correct exposure had to shove the ISO up to its limit. Strangely, readings on that one occasion were within 128 range. Is it acceptable to submit Module 2 with an adjustment to underexpose slightly as I have done to get the correct readings pending any corrections or otherwise Nikon may or may not do? I notice from a Nikon discussion site several people commented about possible slight overexposure with this camera. It is a manageable "problem" so I am not sure whether it is worthwhile taking it up with Nikon- everything else is so great.