Quote Originally Posted by Murray@uptowngallery
Say, I did make an 'x' in pencil on the ground side of the ground glass for some future use. I also wanted to try the oil spot technique in center of the GG.

Will that 'X' and sufficient backlight serve instead of a hair? I had been leery of keeping a hair flat when reading of this technique previously. I wasn't too impressed with 'Scotch Magic' tape flatness prior to cutting ground glass.
We always make pencil marks on GG's - no scotch tape needed and easy to remove later. Plus flatness garanteed.

If only option is three starting points I can only suggest keep trying, as I haven't seen the camera you're talking about. Pics always help (hint).