which target?
Mr. Schmecky:
You describe as either seeing one or the other.
Let's focus. When viewing the front sight, in focus, the target does not actually disappear does it? Or does it just become blurry; indistinct.
But, it is still in your vision isn't it? Take a look the next time you are at the range.
This is a phenomenon of vision that all shooters work with.
Having the front sight in good view permits it's precise alignment to the rear one, and any small error is detectable. The front sight is the actual "target" for your vision.The rear sight too will be out of your focus while doing this.
While a small error in placing the front sight in alignment with the blurry -distant target, is just that; a small error of impact for the bullet.
A slight misalignment of the front sight in the rear one will result in a greater error of bullet placement.
Having explained this however, may I also tell you of my trifocals?
I'm nearsighted. The opposite of you. I have had an "intermediate" prescription ground into the center of my glasses between the larger far distance prescription, and the smaller near vision prescription used for close work like reading. It is a oblong or retangular area that is just below the horizontal center of my lenses, so that I can get a "clear" image of front sights, or any object at "arm's length" from my eyes.
I hope this clears things up a little.
Jim