In response of the article of Andrew Reid from EOSHD, about using wide and fast C-mount on GH2,
eoshd.com/content/512-Is-this-the-scariest-GH2-lens-in-the-world-Computar-8mm-F1.3
here is a test with my (rare) Cine-NIKKOR 10mm 1.1:8 on GH2. Shot on 1080 24P, then edit on 720 24P, You will see 100% of the frame with the vignetting, then a post prod digital 128% zoom to put the vignetting of. You will also see the GH2 crop 1:1 function on the full frame (1:1 crop mode on this 10mm = my other C-mount 25mm with no crop mode).
The back of this lens does not protubing, so no problems for the shutter. I've bought this lens on Ebay for 130$, its weight is 145g. Here's a link of the Cine-NIKKOR lenses :
akiroom.com/redbook-e/kenkyukai09/kenkyukai200904.html
I've done movies with its 25mm 1.1:4 sister :
vimeo.com/album/1525146

GH2 24P edited on a 720 24P sequence
C-mount Cine-NIKKOR 10mm 1.1:8
No CC
full frame, digital post prod crop, 1:1 GH2 crop function

duration : 2mn30sec
music : Godspeed You Black Emperor "The Dead Flag Blues"