Autofocus

Or more correctly, the dangers of autofocus. To make a short story long, I was working with a 28-90mm autofocus lens and in order to get all of the image in the frame that I wanted, I had to keep moving the camera further back, which threw off the frame I had in mind.

Finally I settled on this frame, and the autofocus just would not pick up the aliens. Shot after shot gave me chess pieces in focus, but the aliens were blurred. Finally I got a lock on one, only to have it end up refocusing on the chess bits.

So there's the lesson of the day, if you need focus on a particular subject, switch back to manual.