I have been using so far the Leica lens correction in camera to remove the color shift on the ZM 18 and 25. I found the best equivalents in a list that I received from Zeiss upon request, but it is also available on the Leica user forum. Now while the profiles are successful in removing the color shift entirely on the 25 and and partially on the 18, they happen to remove vignetting in a very unnatural way, that makes the photos look somewhat flat. I prefer the natural vignetting in lenses as it adds to their character.
So any suggestions?