My digital camera does that all the time in dark situations. I hate it - cuz I'm not trying to do that! On the contrary I try to stay as still as possible and I still get that! Blah!
need a better camera and/or tripod.
Or as steadier hand. I had a smalll tripod but it wasn't enough... it was too windy, so many photos ae blurry. But all those 10-15 with moving the camera deliberately look all great.