The basics of iron sight marksmanship require you to focus only on the the front sight. Since your eyes can only focus on one thing at a time, the rear sight is blurred as is the target. With practice,, very tight groups are possible at all ranges. I know this from years of rifle and pistol competition with iron sights. Nothing wrong with good optics, iron sights are still a viable choice for a variety of reasons like com;pact, light weight, durable and effective.
Cheese