While i was working on a HDR timelapse i noticed something strange. I was using the 3 step bracketing (since the D90 doesn't have a firmware update to a 5-step as far as i know). The D90 was mounted on a very firm and stable tripod. The first of the 3 shots (under) of each set was always pointed slightly downwards, the other 2 were perfectly aligned. After taking the 3rd shot it would immediately move back down again even if the next set was several seconds away. It's not a big problem, but i can't find the cause. I tried to look at the camera when it was taking the shots, but it doesn't seem to move. I drew a line were the top of the chimney was suppose to be. OfftopicPS: Yeah, i noticed the buildings were underexposed, so i changed it a little in the next sets.