I tried to shoot my Nikkor 14-24mm on my new 5DIII, and the camera got very confused trying to sort out what the aperature was. It finally threw an error saying there was not a connection to the lens & to clean the contacts. I have the camera in "Manual" mode. I'm using this converter: http://www.adorama.com/CZNKGEOSAF.html
It works great on my 5DII. Has anyone else had good/bad luck in marrying up this lens with the 5DIII?