I have used the 5DIII with Lightroom 4 and the latest version of Capture One with no issues. If you don't have the newest version of either of those, use the EOS Utility on the disc that comes with the camera. It supports not only tethering, but real-time Live View also.
Alton (TN) wrote:
I have been pouring over the reviews, videos, etc. on the 5DIII because mine is on the way. I ran across one review that complained that the 5DIII cannot be tethered using Lightroom or Canon's own software.
Is this true?
For event photography I us a tethered monitor to quickly check my shots and hope that I will still be able to do that.