Mt Spokane Photography said:
aj1575 said:
Here is the real reason why Zeiss does not make AF-Lenses for Canon and Nikon:
http://diglloyd.com/articles/ZeissTouit/ZeissTouit-overview-optics.html
From the Zeiss Q&A:
Because of the patent situation, it is not currently possible to offer a ZEISS AF lens for the other camera systems with EF and F mounts
And also:
In its collaboration with Canon and Nikon, ZEISS currently is not even licensed to use the autofocus interface on the camera.
+1
This is the correct answer, the others are just guessing. Zeiss does not wish to reverse engineer a lens and end up with a poorly focusing one like some other third party lenses. They do have a agreement with Sony, and make AF lenses designs for Sony. They don't actually make the Sony lenses, just license their design and their name.
No, it is not "the correct answer". At least it is by no means "a complete answer".
Zeiss manual lenses for Canon EF mount feature "focus confirmation, metering/operation with all modes (Av, Tv, M, P...) except A-DEP, lens data transmitted to EXIF, distance reporting for E-TTL II". This is not feasible without access to the lens protocol of the Canon EF mount.
Obviously there are hidden "non-competition agreements" between the various players in the camera market ... and Zeiss is playing along by those and refrains from bringing AF lenses for both Canon EF/EF-S and Nikon F mount to market ... while quoting "technical/patent" reasons in public.
Also, at least some of the (original) patents on Canon EF mount and the electrical mount protocol must have expired some time ago [1987 -> 20 or 25 years thereafter -> 2007/2012?].
Similar to the expiration of patents on the Leica M-mount by the end of 1998.