What you can do is encode the lens yourself. I did it with my Older non encoded lenses. I think there may even be a kit out there for DIY 6 bit lens encoding :)

http://www.matchtechnical.com/Pages/coderkit.aspx

Thanks Jorge and Aquilan, I knew there would be the technical expertise here. It all makes sense to me now. I will work some more with both the Leica and Sony bodies with the wider Zeiss lenses (both 28 and 21) It may be I either have to go back to film or step up to Leica 6 bit linked glass - there goes the summer travel budget! Thank you again!!!

This is a known issue. I can't give you the exact scientific details. But for the most part, any wide M lens on a Sony will yield this fringing and vignetting issue. It has to do with the sensor and traditional M mount lenses not designed for a perfectly flat sensor. The way Leica gets around this with their lenses is that they include the 6 bit coding on the lens mount. The digital M camera which ever it may be, identifies the lens based on the code and applies the necessary correction to address this. I know its not what you wanted to hear but it is well documented. I ended up with A7 series camera and native lenses and am anxiously awaiting the Batis 25mm f2 due next month.

I posted this image in hopes someone can help me diagnose the purple/magenta fringing that with my Zeiss G Biogon 21mm f2.8. It occurs with both a Leica M (type 240) and on my Sony A74 using a Metabones adaptor. I contacted Metabones at first because I first noticed the fringing after using the M mount on the Sony. Metabones said the problem was due to the short focal length and the Sony not being able to identify the type of lens because the adaptor did not allow for "communication" between lens and body. I noticed the problem was also evident using the Leica M 240 -anyone here have similar experience and/or been able to fix the issue? I love the 21mm but with this issue my choice is to either crop around the fringing or post process as B&W --- Help!!