Help required for a complete novice. I have a Panasonic Lumix DMC FZ100 and, although I appreciate that it has come in for criticism from purists, at my level of expertise it does the job. However I do have a quandary - on a few occasions (taking a shot of a low lit lamp) when the ISO is set at 100 the picture is taken on an ISO setting of 160. I am NOT using any automatic setting. I'm waiting for Panasonic to get back to me but they're taking their time. Any ideas?