Except that your fovea moves around with your eyes and this is glued to looking straight forward. You get PPD gain if you're looking at the same thing that your

Except that your fovea moves around with your eyes and this is glued to looking straight forward. You get PPD gain if you're looking at the same thing that your face is pointed toward, at the expense of when you look off to the side. Not exactly "free" but probably worth the tradeoff. How big a "sweet spot" do you have in the center? Enough to read lines of small text without rotating your head back and forth?