Sorry I have not been on the forum in a long while. I hope you got your question answered. From what I have found the 21mm on the GH cameras do not have color shift or edge smearing. There is some vignetting though but the images still come out very nicely.
I saw that you have removed the 21mm biogon contax g lens' legs and you are able to mount it on the GH1.
The picture you posted is fantastic but does it have any color shifts? Previously I have trimmed the legs of the 21mm Biogon Contax G lens off and mount them on the Nex-3 and the color shift is horrible and corner fix does not remove everything. Edges are smeared as well. Does this happen on the GH1? Wanted to know as I am about to buy another 21 (I have sold the previous one and never tried it on the GH1 before)
Also are you able to mount the 21 on the GF1 or the pen series as well?