Just curious. Why would you prefer a manual focus lens? I've the 17.5mm and 25mm Voigtlander and I love them for the photos and videos, and also the external aperture ring. I've no problem manual focusing with them on my GH2. The advantage of using manual focus is perhaps, you don't have to press buttons or screen to choose any AF selection points. There's also absolutely no way you can focus on the wrong subject. This is especially true in the dark when focusing speed is slower and sometimes there could be focus inaccuracy. As for focusing speed, it's basically as fast as your hands can go. There's no need to half-press focus.