I don't know what the situation is on Canon. Maybe someone else can chip in. I replaced the mount with a Leitax mount, and this works well on my Nikon. The Dandelion chip gives me focus assist and EXIF (not accurate aperture and distance, etc., just the lens on the camera), but again, I don't know how this works on Canon.

I'm used to getting nothing from my Nikon lenses on the Canon bodies, and have not bothered with the focus assist feature, instead staying with the less expensive Fotodiox manual adapters.

Very interesting lens!

Here is a link to a post I made about this lens in the "Zeiss Lens photos and Discussion" thread:

http://www.fredmiranda.com/forum/topic/1009161/0#9585019