One of my favorite lenses to use on the BlackMagic Pocket Cinema Camera or the Panasonic GH3/GH4 cameras is the Lumix 20mm F/1.7 II Lens. A short small lightweight lens with a wide aperture. On an M43 camera it's capable of achieving a nice blurred background with a subject sharp in focus.
A great portrait type lens with a minimum focusing distance of less than 8" allows for some very creative close up shots. To get an idea, you can see some samples shot on my 20mm F/1.7 in this video (click here).
I highly recommend this lens for MFT shooters. Right now there's an instant savings of $80 dollars off.
Panasonic Lumix 20mm F/1.7 II Lens