Oh boy, loosing 200 minutes due to focus shift, I feel for you Doug, that would drive me crazy.
At least you got some data to use and it's turned out nicely for 100 minutes mate.
I stuffed up in a similar way one night because I hadn't tightened the clam shell onto the mount all the way down, it was just ever so slightly loose giving it a bit of play and half the data was ruined.
