As I have both lenses at the moment I thought I would do a quick and dirty compare. I took a number of shots with both lenses. My choice of shot was mostly decided by the fact that I was most interested in the differences in C/A between the two lenses. Comparing both lenses at 100% I couldnt really make out much difference. One lens would look better than another with the same shot then I would take it again and the other lens would look better. Admittedly my shooting was pretty rough and read. The 12-40 isnt completely without C/A. In this shot, the 12-40 actually shows more C/A than the 12-35. It is at 35mm viewed at 100% with the 12-40 on the left. This shot - a 100% view of 12mm - seems to show the 12-40 is sharper but once again I suspect it is as much focusing error as anything else as there wasnt a consistency over the results.