My viewpoint of Zeiss Glass.
The headquarters for Zeiss is in Oberkochen Germany. I was there last December. If you want to drool then arrange to go to the Museum in the Oberkochen facility. In they museum much of all the artifacts are under glass. Not just any glass, but Zeiss glass. Its amazing stuff. You cannot even tell that there is glass between you and the artifact. But reach out and your hand will fail to penetrate the glass protection.
Its a sight to behold. Looking at a 50mm 1.4 and at first it looked empty as if there was no glass at all. How do they do that? I won't tell. Just take it from me, they couldn't possibly make a poor lens.