There has long been confusion related to focus and it’s quite understandable.
Should you focus on the target, the sights, let everything go blurry and hold you mouth just right? What do the experts do?
According to the NRA, your primary focus should be on your pistol front sight. Even if the rear sight are a bit out of focus, that’s fine.
You simply need to see the rear sights well enough to be able to alight them with the front. The sight configuration in the example below are a variation of the 3-dot setup, our favorite.
If you find yourself having focus issues that can be overcome, then perhaps you might consider install aftermarket sights.