T - don't doubt what you are experiencing at that distance, but both my deer from last year were under 10 yds (tracked less than 50) and I know I had my left eye closed. Don't know how unique my situation is, but I do not have a dominant eye and I am slightly far-sighted in one and slightly near sighted in the other. All I know is it works for me. I will continue to keep both eyes open until that last second though.