I tried this method and Mr. Quick, it is a little hard to see the two cross hair sets. I was able to get them lined up, I think. I noticed that one set was a little distorted or curved out on the ends. There must be a way to get the light source lined up better so that the cross hair sets are easier to see. Is it better to have a point light source like a flash light coming from behind, or just the light in a room?