For just under 400 US dollars, this samyang lens (rokinon or bower) is a gem. The fact that this is f2.0 makes it all the more intriguing and desirable. I have never used a lens wider than 16mm (apsc) and in fact rarely go wider than 20mm (aspc) on my NEX6 so it was rather very interesting experience to see the world in 12mm.
Since everybody else was doing it.. this was a little bokeh test. It has fairly smooth bokeh but by no means... you would buy this lens for bokeh, but it is there for those who need it in emergency.
And yes at f2.0 the center and the edges if focused correctly can be pretty sharp :)
The lens has a very similiar looking flare as Samyang 8mm fish eyes, which I use very often. This is a good thing because I find the 8mm and 12mm both have very nice but not too strong lens flare. Both lenses also share same build quality and looks. IMO, they look very nice on my NEX-6.
I have not done the traditional "brick wall" test, but there is a barrel distortion like any other UWA. Since I enjoy using fisheyes, I don't find the distortion much of an issue for my shooting style. There is no lens correction option in Lightroom so for those looking to do architectural shots will have to manually fix the distortion. I don't find the lack of AF much of an issue either. I usually have it set close to infinity and rarely touch the focus ring. However, I find the focus ring a bit too stiff for my liking; maybe it will loosen up over time.
The very next day I took the lens to shoot out in the creeks nearby. It rained throughout the week which made it a perfect condition for creek shots. I used the newly purchased Hoya ND8 filter. At around aperture 8~11, the lens is sharp all across. It does have chromatic aberration but nothing that Lightroom can't handle.
Overall, this lens is a huge "bang for the buck." I am always surprised at how well these Samyang mirrorless lenses are. Along with 8mm f2.8 fisheyes, this 12mm will stay with my mirrorless kit for a long long time.