**Added**: this now also posted on the Zeiss website, here.
“The MTF graphs […] look quite promising, showing very high contrast, suggesting that performance is near optimal wide open.”
…if you only like sagittal detail, I guess. The high contrast doesn’t seem to apply to tangential details, which even appear relatively worse when the lens is stopped-down.
I agree with Diglloyd, wide-open the lens starts off looking promising, but the gap between sagittal and tangential detail contast (stopped-down) is too important for this league of product. Now if this sounds like a dry theoretical opinion... if sagittal contrast was the determining factor of performance, wouldn't you expect this sample (below) to pop a lot more?
Sample put up by Zeiss in this directory. It's frustrating that Zeiss did not include any samples from which to easily judge sharpness.
Looking at the sample closely I conclude we're seeing detail smearing in the upper right corner. This is consistent with the posted MTF.
I first hoped the test shot was taken at f/3.5 and wouldn’t be indicative of maximum performance, but now we know the corner performance is independent of aperture...
In the end, with its completely new optical formula the ZF Distagon-18 does improve greatly on the MM Distagon-18 but only to net a bias for the orientation of detail. This is rather short of success in my opinion. It is miles behind the MM Distagon-21, which offers even better performance that is independent of orientation.
It’s clear to me that Zeiss will eventually ship a ZF 2.8/21 Distagon, having shipped a 2.8/21 for every other system they supported. I’ll stay put and hope they deliver a home-run like the MM 2.8/21.