SLR Gear, an offshoot website of the Imaging Resource, one of the web's most-trusted resources for all things digital photography, has just posted an in-depth review of the new Panasonic 42.4mm f1.2 ASPH lens, which was designed to be the Micro Four Thirds king of the night.
So, how does it do in practice? Short answer: very well.
Optically, the lens is really good. In terms of sharpness, the lens is good right from the get-go at f1.2, a very impressive feat indeed! The lens does sharpen when stopped down, albeit slightly, peaking in sharpness around f4. In practical terms, though, you probably won't notice any difference in sharpness from f1.2 to f4, though. As for chromatic aberration, vignetting, and distortion, all are very well controlled and should not present any real problems in real-life shooting. The vignetting measurements are especially impressive considering that this is a f1.2 lens, showing less than a stop of falloff
Mechanically, the lens uses all-metal construction and AF via a stepping drive motor, which results in silent, fast (though not as fast as other Panasonic lenses) AF. As for manual focusing capability, this is controlled via an electronic focus ring, which is wide and smooth to rotate. As for what electronic focusing means, it is basically a glorified focus button as there's no mechanical movements of anything inside the lens. Additionally, the lens also features an aperture ring (also electronic) for controlling the lens aperture, too.
If there is one nitpick on this lens, it is, well, there really isn't one aside from the size and weight, which is plainly obvious by reading the specifications. On the other hand, as SLR Gear notes, this is a serious lens for serious shooters who aren't likely to care, anyway. .
Overall conclusion: the Panasonic 42.5mm f1.2 is a great lens “one of the best we've ever tested.”
For more info: