Thanks for the heads up Albert. It'll be interesting to see what the problem might be in mounting the Leica 28-90/2.8-4.5 on an EOS camera. Maybe the rear element protrudes to deep when at a certain focal length and interferes with the mirror... or something like that.
I encountered a non-compatibility issue mounting the Zeiss 60/2.8 Macro on an EOS 1DsMKII. The automatic stop down cam arm was just hitting the mirror box inside the Canon, which was easily remedied with my trusty Dremmel tool. Now it works on the Canon, but if mounted on a Contax body lacks the auto aperture function ... which I could care less about on a Macro lens usually used deliberately and slowly and costs less than $500 used.
But modifying a $3,200 Leica Zoom is another matter.
Asher, who's driven by Zeiss purism? I have, and regularly use Canon EF AF lenses: 14/2.8L, 16-35/2.8L, 24/1.4L, 35/1.4L, 50/1.4, 85/1.2L, 100/2.8 Macro, 135/2L, 70-200/2.8L (sold a 200/1.8L and 400/2.8L for lack of use verses cost ). AF lenses are a must for some applications, and I wouldn't go to a wedding shoot without some of them.
However, we stringently test lenses against one another in a drive to improve image quality as much as possible. In every case where we put a Zeiss lens up against a Canon, the Zeiss visibly won.
Wide angles from Canon are notorious for distortion and lack of sharpness at the edges. Plus, IMO, Canon has always had a sort of pastel coloration in general, which isn't glaringly apparent to the eye until placed next to the same shot done with a Zeiss lenses of the same or similar focal length. It just depends on the characteristics one prefers.
We did side-by-side test a Canon 35/1.4L verses a C/Y Zeiss 35/1.4 @ f/1.4. Both Irakly and I agreed that the Zeiss was better, had nicer out of focus areas and nicer over-all color with richer blacks. The sharpness wasn't an issue with either lens, but sharpness isn't everything I look for in a lens ... the emotional elements are just as important IMO.
As far as Canon Long glass, I'd generally have to agree with you. Superb. The 200/1.8 I used for a long time was wonderful as was the 400/2.8. So, I was surprised when the Zeiss 70-210/3.5
actually outperformed the Canon 70-200/2.8L. Not going to sell the Canon zoom over that issue. AF and IS is a wonderful thing.
Yet, AF and automation, while incredibly useful sometimes alters
a shooting style for the worse. In an assessment of my body of work over the past few years, I found that the images that defined my style and have brought me the most business, were overwhelmingly produced by 3 cameras and related lenses: Leica M, Hasselblad V, and Contax 645 or N with 645 glass (which I tend to manually focus).
But I grew up using manual cameras and learned the focusing tricks and art of anticipation that allows me to get the kind of images I want.