Here is a Youtube video I made tonight showing how moving from inside focus to outside focus looks like with this mask. The difference between one extreme to the other was about 1/8th turn of the rough focus knob of my AP160.

http://www.youtube.com/watch?v=OFZKBop0ILU

While my home made mask works OK, the rough edges do not produce a nice clean defraction line. Time to make a 3rd generation mask... While this is fine for really bright stars, I would like to be able to use my mask on much fainter stars so I wouldn't have to move my scope / camera to check focus during an imaging run.