Thanks and I did compare them already. The 30mm seems to be slightly better as a prime. It is S shaped and I was just wondering if it can be corrected easily. The only way is to see a real lens shooting grids at this point for an easy answer. I did contact Leica and seemed to get no answer.
Through experience my Nikon 17-35 f2.8 was so horrible for interior work. I ended up with the 16-35 f4 to get better result but still there is parabolic shape sometimes… I only dare to use my PC-E with lines near edges at the moment.
Josh Lehrer;4435 wrote: I have not had the chance to test this myself but Leica Camera offers very thorough lens data documents on their downloads page (at the bottom):
http://www.s.leica-camera.com/en/DOWNLOADS
The documents include distortion charts, among other things, and you could compare the distortion of the 30-90mm to the fixed focal length lenses too!