IN the G1 camera, when you're using any mFT or FT series lens, the default setting is to magnify the image in the viewfinder by 5x whenever you're in manual focus mode and touch the focusing ring, and you can jump that up to 10x if you need. This 'MF magnification assist' can also be enabled by pressing the left arrow then Menu button.
With an adapted manual lens, the camera basically doesn't know that there is a lens fitted on the mount: magnification assist is always enabled by pressing the two buttons in sequence.
I'm pretty sure this is the same on the G2, for the most part, but I think the G2 can also do a short cut in enabling the MF assist by pressing the control dial, or something like that.
With 5x and 10x viewfinder image magnification available at the touch of a button, these are some of the easiest cameras ever to nail critical focus even in miserable conditions.