Lens with two apertures

As you might have experienced that squinting human eye can able to see outside world slightly sharper...

With that, Will adding an another aperture to an existing lens produces any sharper pictures, provided both apertures have same or different opening?

Just curious...

raavi wrote in post #12637429
As you might have experienced that squinting human eye can able to see outside world slightly sharper...

With that, Will adding an another aperture to an existing lens produces any sharper pictures, provided both apertures have same or different opening?

Just curious...

When you're squinting you're just getting a pinhole camera effect. Where a small pencil of rays goes to pretty much the same imaging point (where as when you're not squinting and not corrected for any refractive error you're not getting rays going from a single object point to a single(ish) image point. So all you're doing is really stopping the lens down (if you want to talk in photography terms).

Some gentleman has posted this

http://www.the135stf.n​et/index.html

on an another forum.

Ross Murray wrote in post #12637471
When you're squinting you're just getting a pinhole camera effect. Where a small pencil of rays goes to pretty much the same imaging point (where as when you're not squinting and not corrected for any refractive error you're not getting rays going from a single object point to a single(ish) image point. So all you're doing is really stopping the lens down (if you want to talk in photography terms).

I believe some expensive zoom lenses do use two stop apertures inside - perhaps one is used at one FL end, and the other one at the other end. It is also possible that both are used at the same time, to maximize quality in the frame corner.

Regarding "smaller aperture means sharper image": it works only as long as light diffraction around the aperture stop is negligible. Diffraction kicks in around f/5.6-f/8.0 on most lenses, and at smaller apertures you start loosing your resolution.

Things get sharper for you when you squint?!?!? Maybe if you're eyes are going, I dunno.

phreeky wrote in post #12638330
Things get sharper for you when you squint?!?!? Maybe if you're eyes are going, I dunno.

No he's right, next time your at a shop that sells the ready readers put on a pair of them (more powerful the better) and look at a distant object. If you're an emmetrope it'll be blurred. Now screw up your eyes, you'll see it becomes sharper.