Thanks for the work, philber, it is certainly appreciated by me at least, because it is one thing to do these comparisons oneself and entirely another to publish them, with the extra time commitment, file prep etc.
After your earlier post, I checked out the MTF of the two wide Leicas you mentioned, this 24mm Elmar and the 21mm as well. As you know I believe MTF (where accurate) to be a scientific representation of lens performance. Yes, we know the limits, but in terms of sheer contrast levels and resolution, MTF is it. The MTF charts of these two Leicas are very, very close and both are extremely good, guaranteeing image brilliance and fine resolution levels across the frame. To be sure, the 24mm is this one: 'Elmar-M 24mm f3.8 Asph'? If so, a little slower, f3.8.
To your near-centre crops: what I find interesting is the lack of apparent contrast the 24ZA shows, which co-occurs with high resolution at fine levels (micro-contrast). I tried downloading but the crops come up as php script files, and PS would not open them for me. The density of the two images is almost identical, in a pixels per file size ratio. Not surprising as the 24ZA is a very good performer, and even show some details not apparent in the Leica image. I'll bet the histos tell an interesting story! There is clearly a tone level difference but also contrast differences, and the very obvious colour transmission differences, these last two significantly affected by the first. [Some of this one sees in each company's other offerings, of course.] Shadow detail is very similar..but the midtones are night and day, and would remain even if tone range was 'equalised' in post.
BTW, iskaII, that MTF data is highly misleading, being so optimistic that it belongs in a fairy tale. Zeiss would be first to agree I am sure.
What it does show however is that the lens has consistent contrast from the centre to the edges of the APS-C frame wide open, with the centre at a much higher level. At f8, things are quite different, the midle of the image improves greatly, and we see a significant drop-off in fine detail from mid-frame and edge degradation due to separated lines and the kickup for 40 lpmm sagittal. In a nutshell, optimised for wide open use and centre-based images stopped down, not a landscape lens!
Why don't Zeiss themselves publish ZA series MTF on their website? Their name is on the lens...I have no idea, but we are poorer for the omission.