Randy is absolutely correct. That is the essence of using aperture or open sights. Focus on the front sight.........it is the front sight that must be crystal clear in focus. The target may be slightly blurred or fuzzy and that's okay. When you focus on the target instead you lose sight alignment. Of course, younger eyes do this better than old eyes, but the principle is the same and must be adhered to for best accuracy.........focus on the front sight!!!!!