With more companies getting into the lens adapter business, adapters are getting better and more sophisticated; they are getting smart too. Old adapters were purely mechanical and there was no electronic linkage between adapter and camera, but that has changed. First we had the EOS-NEX adapter by Metabones, that allows the NEX camera to control aperture of Canon EF lenses from the NEX camera. Since then, various Chinese adapter makers introduced their own, with image stabilization and AF support. They are also readying the Contax-G rangefinder to NEX adapter that allows auto focus.
The latest, and the best news, is the Metabones SpeedBooster adapters that makes full frame lenses behave the same on NEX or M4/3 cameras by angle reduction. It behaves the opposite of lens extenders, with an added benefit of increasing the maximum aperture by one stop. So, your EF 24mm f1.4 will have basically have the same angle of view on the NEX camera, but at f1.0 instead. The optical lens in the adapter was designed by the very well known Dr. Brian Caldwell. So, all is well, right? Yes and no. The price is very steep. Yup, $600 for the adapter. Unlike mechanical adapters that can be copied/cloned, the optics in the adapter is pretty hard to copy without being sued. So, don't expect the price of this great adapter to get cheaper any time soon.
Cherry Blossom in Infrared - Canon 20D IR & Pentax-M 20mm f4.