I never don't try other non-Canon options. The best from Canon in that range may be the 17-40L, but CA and performance decrease in the edges (on the 1Ds) are remarkable. The Zeiss is in another class.
med007 wrote:
The 19mm Leica lens upto the 35mm lens have too much protrusion at the back to allow mounting w/o hitting the Eos mirror housing.
The Leica lens in question is R mount, and has a retrofocus design to clear an SLR mirror. My reading of the 19mm MTF is it looks really good, but it's even more expensive than the CZ.
The WA Leica M lenses would hit the mirror, as you say. For example, I measure 20mm free space from lens chassis to focal plane for the Summicron-M 35, and a much larger 35mm for the Canon EF 35/2. There's also the matter of microlens vignetting with the older WA RF designs.