I was looking at your videos again, and I noticed you use the Kipon EOS to m4/3 mount adapter? Is this the only, or best adapter to use with the 30mm 1.4?
For modern lenses like the Sigma 30mm, aperture is usually controlled internally / electronically. To adjust aperture on a camera that the lens wasn't originally designed for (gh2 in this case), you need an adapter which has an internal iris / aperture to stop light for you. The kipon is probably still the best adapter available and the only one (I think), that has this internal iris / contracting aperture blades (there are many others, but without an iris / aperture). It's worked great for me and is pretty much a necessity. Good thing about this adapter is that many newer modern lenses are produced in Canon mount, so whatever ef(s) lenses or other canon mount lenses you happen across, will easily adapt to your gh2 with a real working iris / aperture.
Great thing about vintage lenses though, is that they have an external aperture ring that you can adjust manually at will, all you need is any decent cheap adapter to mount your chosen lens onto the gh2 (m4/3); most of these adapters are only about $20-$30.
