Quote Originally Posted by lxdude View Post
Nope. Not against the laws of physics.
In fact, a perfect lens, i.e., one without aberrations, has its resolution limited only by diffraction. The larger the aperture, the more the resolution. Every doubling of aperture diameter, e.g., f/8 to f/4, results in doubling of resolution.

It's just that in the real world things aren't as easy as that.
To elaborate a bit further, every real and theoretical lens gets more diffraction with narrower apertures, that's physics and there's no way around it. So opening wider, every lens gets sharper.
But at the same time, counteracting that, every real lens gets sharper by stopping down, because it removes a lot of abberations that exist in 'real' lenses.
Put the two together, and you get that typical 'hill' curve where stopping down first increases resolution (to f/5.6-8 or so), then stopping down it gets worse again. If you could build real lenses as well as theoretical ones, with f/1.0 and no abberations wide open, besides having to mortgage your house for it, it would only get sharper wider open and be the sharpest lens ever. (and then it would only get used by some nerds who sit in their basement and take photos of Imatest charts and drool over numbers)