At almost 67 yeas of age, my bi-focals keep getting thicker. I prefer A/O tactical scopes, but have experienced focus issues with my Leupold Mark 4. At 100 and 200 yards each, after I adjust the Objective side focus to make image as crisp as possible, the x hairs dance if I slightly move my head. If I remove the parallax (no dance), the image blurs more. My fixed Objective Swarovski and Schmidt Bender all have parallax removed at 200. The x hairs don't dance and the images are real crisp. This A/O adjustment may be a common issue with bi-focal users. I have also noticed it on my Leupold LPS, but it not nearly profound as the Mark 4. Have any old times had similar issues??????