I have the 120 Black Diamond. The only thing I found was that the focus lock still changes the focus after you have got it perfect. The only choice was to leave it unlocked but then as the scope rolls over during the night the weight of the camera causes the focus to shift and you have a problem again.
So I built my own zero shift focus lock stop-plate assembly.
http://www.asignobservatory.com/inde...=81&Itemid=120
Baz.